The Christian crusaders were weary and close to defeat. The Muslim armies defending the Holy Land were much stronger and better prepared than they had expected. Defeat was close at hand and they were about to abandon their question to liberate Jerusalem from the infidels.
Yet they knew they had a secret weapon. The crusaders knew there was a powerful Christian king living in the east, who at that very moment was leading a mighty army to save them. This king was named Prester John, but unfortunately he never came. Some said his army was unable to cross the Tigris river. Others said that it was not yet the time for him to come. And others said that Prester John was a myth and did not actually exist.
Stories of Prester John, also known as Presbyter John or John the Elder circulated throughout medieval European Christian.
In 1165 a letter was received by Byzantine Emperor Manuel I Comnenus which was believed to be from the great king himself. The letter states that John, lives in the land beyond India, where, “Our land streams with honey and is overflowing with milk.” He is so powerful that he is served by 72 kings of the surrounding lands. He sent Manuel a fantastic description of his country:
“Our land is the home of elephants, dromedaries, camels, crocodiles, meta-collinarum, cametennus, tensevetes, wild asses, white and red lions, white bears, white merules, crickets, griffins, tigers, lamias, hyenas, wild horses, wild oxen, and wild men — men with horns, one-eyed men, men with eyes before and behind, centaurs, fauns, satyrs, pygmies, forty-ell high giants, cyclopses, and similar women. It is the home, too, of the phoenix and of nearly all living animals.”
Of course, the letter turned out to be a forgery, but nevertheless, a large part of the Christian world believed in this great king who would come to save them.
Even some Jews believed in Prester John. Joshua ben Joseph ibn Vives al-Lorqui (Joshua Lorki) was a 15th century Jewish doctor living in AlcaƱi, in Aragon, Spain. He served Benedict XIII and wrote a medical textbook in Arabic which was later translated into Hebrew as Gerem Hamaalot.
In a letter to Paul of Burgos (a Spanish Jew who converted to Christianity), Lorki wrote:
I know that it is certainly not hidden from you the matter well-known to us from stories of travelers who journeyed the length and breadth of the world, and also from letters of the Rambam, and we heard it from the traders from the ends of the earth… about those who dwell at the end of the earth in the land of Ethiopians, called Al-Chabash, and they made a deal with the Christian prince called Prester John…
By this time the legend of Prester John had him living in Africa. As the Indian subcontinent became more widely explored and better known, the Europeans realized that the great Christian King must reside in Ethiopia.
There were many attempts at forging ties between European countries and Ethiopia during the Middle Ages, and despite the denial of the Ethiopians, the Europeans continued to insist their King was Prester John.
Zara Yaqob was emperor of Ethopia from 1434 until his death in 1468. In 1441 he sent delegates to the Council of Florence where, despite their confusion and subsequent denials, the council prelates continued to refer to their monarch as Prester John (in Robert Silverberg’s “The Realm of Prester John”).
As late as 1751, the Czech missionary Remedius Prutky visited Ethiopia and asked Emperor Iyasu II about Prester John. He writes that Isayu was “astonished, and told me that the kings of Abyssinia had never been accustomed to call themselves by this name.”
Gradually the legend of Prester John died away but it continues to have an influence to this day. From Shakespeare’s Benedick, who offers Don Pedro to “…bring you the length of Prester John’s foot…” in “Much Ado About Nothing,” to appearances in issues of Marvel’s “Fantastic Four” and “Thor” to DC comics who featured him in “Arak: Son of Thunder” the legend lives on.
This was not the first time a nation waited for a powerful king from a distant land to come and save his people. It was not even the first time Ethiopia was the believed hidden refuge of a powerful king.
In this week’s Torah reading, Shemot, we are introduced to Moses who was saved from Pharaoh’s decree by Pharaoh’s daughter and raised in the royal palace. He was forced to flee after he killed an Egyptian who was persecuting an Israelite and was sentenced to death (Exodus 2:15). The same verse states that he went to Midian, where he eventually married Jethro’s daughter Zipporah.
We are not told how young Moses was when he fled Egypt, but he was 80 years old when he led the Jews out of Egypt. It seems that there are many decades unaccounted for by the Torah.
Although there is no mention of it in the Talmud or early Midrashim, several of the Torah commentaries say that Moses spent the intervening years ruling Ethiopia.
The verse states, “Miriam and Aaron spoke about Moses because of the Ethiopian woman he married, for he had married an Ethiopian woman,” (Numbers 12:1). Ibn Ezra and Rashbam, in their commentaries on that verse, explain that Moses married this wife while he was king of Ethiopia. Later commentaries including Sefer Hayashar, Menahem Azariah da Fano (Ma’amar Chikur Din 3:5) and Rabbi Shmuel Bornsztain (Shem Mishmuel, Beha’alotecha 5676) speak of Moses’s time in Ethiopia. The medieval Midrash Yalkut Shimoni and the 17th century Yalkut Reuveni compiled by Rabbi Reuven Hoshke HaKohen also speak of Moses’s time ruling Ethiopia before he went to Midian.
But the origins of this legend date back to the second century BCE, hundreds of years before the Mishna and Talmud were compiled. The Jewish historian Artapanus, who lived in Egypt, most likely in Alexandria, wrote of Moses’s conquest of Ethiopia in his history book “Concerning The Jews.” Although the book no longer exists, Eusebius, who served as Bishop of Caesarea from 314 CE quotes sections of what Artapanus wrote about Moses. He describes how Pharaoh, named as Chenephres, sent Moses to lead an unskilled army against Ethiopia. Contrary to expectations Moses was victorious and founded the city of Hermopolis and taught the Ethiopian men to circumcise themselves.
Titus Flavius Josephus, the first century Jewish rebel turned Roman historian, gives more details of Moses in Ethiopia. He writes in The Antiquities of the Jews (Book II; chapter 10) that not only was Moses victorious but he also married an Ethiopian princess:
“Tharbis was the daughter of the king of the Ethiopians: she happened to see Moses as he led the army near the walls, and fought with great courage… she fell deeply in love with him; and upon the prevalancy of that passion, sent to him the most faithful of all her servants to discourse with him about their marriage. He thereupon accepted the offer, on condition she would procure the delivering up of the city…; and when Moses had cut off the Ethiopians, he gave thanks to God, and consummated his marriage, and led the Egyptians back to their own land.”
So, according to these ancient Jewish traditions, when Moses stood before God at the burning bush he was not merely a poor, humble shepherd, but also a former hero who had conquered foreign lands and ruled over them.
Yet at first Moses refused God’s command to go back to Israel and redeem the Israelites. Not only did he tell God he was unworthy, but he claimed that the people would not believe in him. And for doubting the faith of the nation Moses was punished.
Belief in a savior from afar does not require evidence or proof. When Moses returned to Egypt he performed the signs that God had given him, but it was unnecessary. For the verse states that immediately, “The people believed. And they heard that God had remembered the Children of Israel and that he had seen their suffering. And they bowed and prostrated themselves,” (Exodus 4:31).
The Torah tells us that Moses came from a distant land and brought the Israelites out of slavery. And just as the medieval faith in Prester John, the belief in a strong leader who will suddenly appear and save a nation remains powerful to this day.
Thursday, December 27, 2018
Monday, December 24, 2018
Parshat Vayechi: The Final Journey
This was originally published on the Times of Israel website.
The elaborate funeral Joseph gave his father may shed light on the mysterious talmudic claim that Jacob never died
On November 30, 2018, George H. W. Bush, the 41st president of the United States, passed away at his home in Houston, Texas, nine months after the death of his wife Barbara. On December 3, his body was flown from Ellington Base to Washington DC, where it lay in state at the Capitol for two days, followed by a funeral service attended by President Donald Trump and three former presidents.
Then his body was flown back to Texas, where a second funeral service was held.
Finally, his body was transported by train to the George Bush Presidential Library where he was buried next to his wife. Mourners lined the tracks as a Union Pacific locomotive named Bush 4141 pulled the carriages carrying the former president and his family the 100 kilometers (70 miles) to his final resting place.
Bush was the first president in almost 50 years to make his final journey by train, but it is a tradition going back to John Quincy Adams, who died 170 years ago.
However, it was Abraham Lincoln, assassinated in 1865, for whom the final train ride became an outpouring of national grief shared by mourners across the country.
After lying in state for a week in the capital, Lincoln’s body was transported 2,662 kilometers (1,654 miles) from Washington to his hometown of Springfield, Illinois in a trip that took almost two weeks.
Along its journey through seven states retracing Lincoln’s journey to the White House four years earlier, the train stopped in Baltimore, Harrisburg, Philadelphia, New York, Albany, Buffalo, Cleveland, Columbus, Indianapolis, Michigan City, and Chicago. In each place, his body was taken off the train and traveled on a horse-drawn hearse to a public building to lie in state as altogether millions of Americans paid their final respects to Lincoln.
As an interesting historical aside, according to President Theodore Roosevelt’s widow, Edith, a young Theodore and his brother Elliott can be seen in a photograph of Lincoln’s funeral procession, looking out of the open second story window of their grandfather Cornelius Van Schaack Roosevelt’s home at the corner of Broadway and Union Square in New York.
A local reporter described Lincoln’s funeral train as it pulled in to Springfield:
This week’s Torah reading describes in great detail the first and only “state funeral” in the Bible. It depicts Jacob’s death in Egypt and his final journey to be buried in the Cave of the Patriarchs in Hebron.
Although nowadays Jewish custom favors a burial in plain shrouds as soon after death as possible, Jacob’s funeral was the opposite of that.
The patriarch passed away peacefully aged 147, surrounded by all his children. Then his body was embalmed and lay in state in Egypt for 40 days while the Egyptians mourned him. Then his body was transported to the border of Canaan, accompanied by a military cortege and all the dignitaries of Egypt. Genesis chapter 50 then describes how the entire entourage was joined by the Canaanite people in a place named Goren Haatad for a further seven days. The site was renamed Evel Mitzrayim (Mourning of Egypt) to commemorate the event.
Although the Bible says that this was “on the other side of the Jordan” it seems unlikely that Jacob’s funeral procession made such a wide detour. Aaron Demsky (along with other scholars) explains it is more likely that Jacob’s final journey followed the Way of Horus, which was the main route from Egypt to Canaan. It is probably that Goren Haatad was a small village that was later destroyed during a Muslim battle with local Christians on February 4, 634 CE (described in Latin in Anecdota Syriaca p. 116).
Only after the weeks-long public mourning by the Egyptians and the Canaanites did Jacob’s children bury his body in the Cave of the Patriarchs, alongside Abraham and Sarah, Issac and Rebecca, and Jacob’s first wife Leah.
Yes, there were perhaps bigger funerals in Jewish history — when Miriam and Aharon died in the desert they were mourned by the entire camp of 600,000 military-aged men, as well as the women and children. But nobody else in the Bible was mourned publicly by all the surrounding non-Jewish nations.
The people came to mourn Jacob, but the entire event was arranged and coordinated by his son Joseph, who was still the second-in-command in Egypt at the time.
It must have been so painful for Joseph to arrange such a public and international burial for his father when Jacob was unable to give Rachel, Joseph’s mother, even the bare minimum of a funeral. Although she married Jacob after Leah, and thus was his second wife, she was also the patriarchs first love, and when she predeceased her sister maybe Joseph had hoped that she would be buried in the Cave of the Patriarchs so she could remain alongside her husband in death.
But instead, Jacob apologized to his son, saying that he could not even bring Rachel’s body to the city but buried her at the roadside (Genesis 48:7).
Despite, or perhaps because of, the ignoble burial Jacob gave Rachel, Joseph swore to his father that he would carry him to Israel for burial with his fathers. And he gave Jacob the most elaborate public and international funeral recorded anywhere in the Torah.
But why did Joseph give his father a state funeral?
George Bush planned to make his final journey by train, perhaps as a reminder of how as a child, he rode the rails with his family, sleeping in on the train. Or perhaps he wanted to remind the country of an earlier age, when the only way to cross the country was by locomotive.
Why did Lincoln’s family and advisers decided to hold a very public funeral for him? Perhaps it was so that the nation, shocked by his assassination, could mourn for him publicly. Or perhaps it was a show of defiance against those who opposed his views on emancipation.
But why did Joseph give his father such an elaborate funeral? Jacob simply requested that he be buried in Hebron.
Perhaps it had to be done so that the Egyptians would continue to respect him and his family. During the New Kingdom period ancestor worship and honoring one’s deceased parents was not only important, but the Egyptians believed that if the family treated their deceased with respect, the dead would be able to continue to have an influence over the affairs of the living. Maybe the Egyptians insisted on a drawn-out, public funeral for their leader’s father, to ensure that the Patriarch would continue to protect his ruling son and the entire nation.
Or perhaps Joseph was preparing for the long exile of the fledgling Israelite nation. God had promised that Abraham’s descendants would be strangers in a strange land for hundreds of years. Maybe Joseph planned the elaborate funeral and procession to Israel so that even in the darkest depths of enslavement, Jacob’s children could look back and remember a time when their father was so important to their oppressors.
Or maybe Joseph wanted them to always remember that they were in exile, and that their ultimate destination was the land of Canaan. Jacob’s funeral would have remained as part of the narrative of the Egyptians and Canaanites for a long time, acting as a constant reminder to all that Jacob’s children ultimately belonged in the land of Israel.
Perhaps this is another meaning of the talmudic concept that Jacob never died:
Maybe Jacob remains alive for his descendants as a constant reminder that once upon a time he and his family were respected by all the surrounding nations. And that eventually his children will follow his path, leave their exile and return to the holy land.
The elaborate funeral Joseph gave his father may shed light on the mysterious talmudic claim that Jacob never died
On November 30, 2018, George H. W. Bush, the 41st president of the United States, passed away at his home in Houston, Texas, nine months after the death of his wife Barbara. On December 3, his body was flown from Ellington Base to Washington DC, where it lay in state at the Capitol for two days, followed by a funeral service attended by President Donald Trump and three former presidents.
Then his body was flown back to Texas, where a second funeral service was held.
Finally, his body was transported by train to the George Bush Presidential Library where he was buried next to his wife. Mourners lined the tracks as a Union Pacific locomotive named Bush 4141 pulled the carriages carrying the former president and his family the 100 kilometers (70 miles) to his final resting place.
Bush was the first president in almost 50 years to make his final journey by train, but it is a tradition going back to John Quincy Adams, who died 170 years ago.
However, it was Abraham Lincoln, assassinated in 1865, for whom the final train ride became an outpouring of national grief shared by mourners across the country.
After lying in state for a week in the capital, Lincoln’s body was transported 2,662 kilometers (1,654 miles) from Washington to his hometown of Springfield, Illinois in a trip that took almost two weeks.
Along its journey through seven states retracing Lincoln’s journey to the White House four years earlier, the train stopped in Baltimore, Harrisburg, Philadelphia, New York, Albany, Buffalo, Cleveland, Columbus, Indianapolis, Michigan City, and Chicago. In each place, his body was taken off the train and traveled on a horse-drawn hearse to a public building to lie in state as altogether millions of Americans paid their final respects to Lincoln.
As an interesting historical aside, according to President Theodore Roosevelt’s widow, Edith, a young Theodore and his brother Elliott can be seen in a photograph of Lincoln’s funeral procession, looking out of the open second story window of their grandfather Cornelius Van Schaack Roosevelt’s home at the corner of Broadway and Union Square in New York.
A local reporter described Lincoln’s funeral train as it pulled in to Springfield:
In the mellow air and bright sunlight of this May morning, sweetened by the rain of last night, when those prairies are clothed in flowers, and the thickets of wild fruit trees, and blossoming orchards are jubilant with birds, he comes back.
This week’s Torah reading describes in great detail the first and only “state funeral” in the Bible. It depicts Jacob’s death in Egypt and his final journey to be buried in the Cave of the Patriarchs in Hebron.
Although nowadays Jewish custom favors a burial in plain shrouds as soon after death as possible, Jacob’s funeral was the opposite of that.
The patriarch passed away peacefully aged 147, surrounded by all his children. Then his body was embalmed and lay in state in Egypt for 40 days while the Egyptians mourned him. Then his body was transported to the border of Canaan, accompanied by a military cortege and all the dignitaries of Egypt. Genesis chapter 50 then describes how the entire entourage was joined by the Canaanite people in a place named Goren Haatad for a further seven days. The site was renamed Evel Mitzrayim (Mourning of Egypt) to commemorate the event.
Although the Bible says that this was “on the other side of the Jordan” it seems unlikely that Jacob’s funeral procession made such a wide detour. Aaron Demsky (along with other scholars) explains it is more likely that Jacob’s final journey followed the Way of Horus, which was the main route from Egypt to Canaan. It is probably that Goren Haatad was a small village that was later destroyed during a Muslim battle with local Christians on February 4, 634 CE (described in Latin in Anecdota Syriaca p. 116).
Only after the weeks-long public mourning by the Egyptians and the Canaanites did Jacob’s children bury his body in the Cave of the Patriarchs, alongside Abraham and Sarah, Issac and Rebecca, and Jacob’s first wife Leah.
Yes, there were perhaps bigger funerals in Jewish history — when Miriam and Aharon died in the desert they were mourned by the entire camp of 600,000 military-aged men, as well as the women and children. But nobody else in the Bible was mourned publicly by all the surrounding non-Jewish nations.
The people came to mourn Jacob, but the entire event was arranged and coordinated by his son Joseph, who was still the second-in-command in Egypt at the time.
It must have been so painful for Joseph to arrange such a public and international burial for his father when Jacob was unable to give Rachel, Joseph’s mother, even the bare minimum of a funeral. Although she married Jacob after Leah, and thus was his second wife, she was also the patriarchs first love, and when she predeceased her sister maybe Joseph had hoped that she would be buried in the Cave of the Patriarchs so she could remain alongside her husband in death.
But instead, Jacob apologized to his son, saying that he could not even bring Rachel’s body to the city but buried her at the roadside (Genesis 48:7).
When I came from Paddan, Rachel died on me in the land of Canaan along the way, some distance away from Ephrat; and I buried her there on the way to Ephrat, which is Bethlehem.
Despite, or perhaps because of, the ignoble burial Jacob gave Rachel, Joseph swore to his father that he would carry him to Israel for burial with his fathers. And he gave Jacob the most elaborate public and international funeral recorded anywhere in the Torah.
But why did Joseph give his father a state funeral?
George Bush planned to make his final journey by train, perhaps as a reminder of how as a child, he rode the rails with his family, sleeping in on the train. Or perhaps he wanted to remind the country of an earlier age, when the only way to cross the country was by locomotive.
Why did Lincoln’s family and advisers decided to hold a very public funeral for him? Perhaps it was so that the nation, shocked by his assassination, could mourn for him publicly. Or perhaps it was a show of defiance against those who opposed his views on emancipation.
But why did Joseph give his father such an elaborate funeral? Jacob simply requested that he be buried in Hebron.
Perhaps it had to be done so that the Egyptians would continue to respect him and his family. During the New Kingdom period ancestor worship and honoring one’s deceased parents was not only important, but the Egyptians believed that if the family treated their deceased with respect, the dead would be able to continue to have an influence over the affairs of the living. Maybe the Egyptians insisted on a drawn-out, public funeral for their leader’s father, to ensure that the Patriarch would continue to protect his ruling son and the entire nation.
Or perhaps Joseph was preparing for the long exile of the fledgling Israelite nation. God had promised that Abraham’s descendants would be strangers in a strange land for hundreds of years. Maybe Joseph planned the elaborate funeral and procession to Israel so that even in the darkest depths of enslavement, Jacob’s children could look back and remember a time when their father was so important to their oppressors.
Or maybe Joseph wanted them to always remember that they were in exile, and that their ultimate destination was the land of Canaan. Jacob’s funeral would have remained as part of the narrative of the Egyptians and Canaanites for a long time, acting as a constant reminder to all that Jacob’s children ultimately belonged in the land of Israel.
Perhaps this is another meaning of the talmudic concept that Jacob never died:
Rav Yitzhak said, “Rabbi Yochanan said, ‘Jacob our father didn’t die.'” [Rav Nahman] said to him, “Was it for nothing that they eulogized him, embalmed him and buried him?” [Rav Yitzhak] said to him, “I derived it from a verse… Just as his descendants are alive, so he too is alive.”
Maybe Jacob remains alive for his descendants as a constant reminder that once upon a time he and his family were respected by all the surrounding nations. And that eventually his children will follow his path, leave their exile and return to the holy land.
Sunday, June 24, 2018
Whose blood is redder?
Here is a rough draft of a script I wrote a couple of years ago about blood. Doesn't really fit with the rest of the stuff on this blog (but not much does), but I still find blood completely amazing, and wish we had managed to make this into a short video clip, as was once the plan.
Script - Blood
The Talmud states that one may transgress any of the sins of the Torah to save one’s life with only three exceptions. One may not commit idolatry, sexual immorality or murder even to save one’s life.
The Talmud finds a source in the Torah to show that one may neither transgress idolatry or sexual immorality, even if it costs one his or her
life. However, with regard to murder, the Talmud says in the name of Rava that it is based on logic:
What makes you see that your blood is redder than his?
Perhaps the blood of that man is redder than yours?
Clearly this expression is not actually related to the color of blood, but rather shows that we never know the value of a human life, and one
cannot decide that his own life is worth more than that of another.
But have you ever stopped to wonder why your blood is red? We take it for granted. We describe people as “Red Blooded.” But why? Or
perhaps our blood is really blue, because when I look at the veins through my skin, it looks as though everything is blue.
[Nigel Tufnel: This is my exact inner structure, done in a tee shirt. Exactly medically accurate. See? It is green. You see how your blood looks blue.]
The answer is that the blood of humans and all vertebrates looks red because of the red blood cells which carry an important protein molecule called hemoglobin. Hemoglobin carries oxygen from the lungs to the rest of the body where it releases it to provide energy.
Now did you know that most of your blood is actually water. More than half of your blood is plasma, which itself is 92% water. The average human adult has between 4.7 and 5.0 liters (14-18 pints) of blood in their body. This is about 7% of your total body weight.
But let’s get back to hemoglobin.
Hemoglobin is a protein which contains four iron ions. Each of these ions bonds with an oxygen molecule and transports it to where it is
needed.
Here is a picture of the four hemes, each containing the iron ion, surrounded by four globins.
Now there are 270 million of these hemoglobin proteins inside each red blood cell.
So imagine a train with 270 million carriages. Each carriage has four seats. In each seat is on oxygen molecule. Everyone boards the train
at the first station, which in the body is the lung. As the blood cells pass the lungs they grab their oxygen.
[Reuven can demonstrate this with a toy train (though I doubt we’ll have 270 million carriages]
The problem is that each of these carriages has a different destination.
Every part of your body needs oxygen. However some parts need it more urgently, or in greater quantities than other parts. For example,
if you are going for a run, your leg muscles are going to need more oxygen than some other parts of your body.
The hemoglobin train has to know where to drop off the occupants of each carriage. How does it know how to do this? Obviously there is
not really a conductor on board the hemoglobin train, telling each molecule when to disembark. However the chemicals act as if they
know where to go.
The answer is Allosteric Inhibition. (Things bind to other parts of the protein, which affects the ability of the protein to do what it normally
does).
Hemoglobin is allosterically inhibited by CO2.
When you exercise, your muscles produce large quantities of CO2.
When the hemoglobin train reaches the station with the CO2, it releases its oxygen automatically, which means that the O2 is
delivered to exactly the right place at the right time.
(Red blood cells are 25% bigger than the smallest capillaries, and have no nucleus so they are
squeezed through them which helps them release the O2).
Now we have already said that each red blood cell has 270 million hemoglobin proteins. But there are also about 20-30 trillion red blood
cells in our bodies. Which means that red blood cells are almost a quarter of all the cells in your body! And if you multiply 270 million by
20-30 trillion you will find that you have an enormous amount of hemoglobin in your body.
This wonderful protein and its amazing chemical properties are what enable all of us to live. Without this we would not last at all.
This is also the reason that our blood is red. Because the hemoglobin is built around iron, which is red. When the hemoglobin is carrying oxygen the blood is a lovely bright red color. When all the occupants have disembarked from the train, the blood looks darker red.
Not all animals are red blooded though. For example, Leech blood is green because it contains chlorocluroin instead of hemoglobin. This is a different protein without the iron, but which also binds to oxygen.
And crabs use copper instead of iron to transport oxygen in their hemocyanin. As a result their blood is blue. This certainly gives a new meaning to the concept of “Blue Blooded.”
So why does our blood look blue through our skin? This is actually due to the way different wavelengths of light penetrate your skin, are absorbed and reflect back to your eyes — that is, only high-energy (blue) light can make it all the way to your veins and back. It has nothing to do with the color of the blood or the veins.
The blood collects the oxygen from the lungs, then begins its trip around the body. Blood carrying oxygen flows through arteries. After it
has dumped its oxygen the blood returns to the heart and lungs through veins. The blood reaches the actual places where it is needed
by squeezing through tiny capillaries. This network of blood vessels covers the entire body.
I have here a ball of string. It is 10m long. I can keep pulling it for quite a while before I get to the end. But the number of blood vessels in your body is much longer than that.
In fact if you were to lay out all of the arteries, capillaries and veins in your body end-to-end, they would stretch about 60,000 miles (100,000 kilometers). What's more, the capillaries, which are the smallest of the blood vessels, would make up about 80 percent of this length.
By comparison, the circumference of the Earth is about 25,000 miles (40,000 km). That means a person's blood vessels could wrap around the planet approximately 2.5 times!
Think about that for a second. Isn’t that amazing!
Now, how long does it take for your blood to make the trip around your body? It is pumped by your heart and needs to travel great distances to get to where the oxygen is needed. Remarkably, it only takes 20 to 60 seconds for a drop of blood to travel from the heart, through your body, and back to the heart again.
In 24 hours, the blood in the body travels approximately 12,000 miles, amazingly that’s four times the width of North America.
Even while you are resting, your blood is working hard for you.
Red blood cells are very important, because they transport the oxygen around your body and keep you alive. Red blood cells live for about 120 days, before self-destructing.
But your blood also contains other important elements.
Blood is made up of red blood cells, white blood cells and plasma
White blood cells are part of your body’s immune system, your defense against infection and other contaminants. White blood cells are also called leukocyte, which is a Greek word basically meaning “White hollow cells” which is a more or less accurate description of them.
Some white blood cells are lymphocytes which are actually made up of three different kind of cells – T-cells, B-cells, and the wonderfully named “Natural killers”. As well as circulating with your blood, most of the lymphocytes actually circulate though the lymph system. But a discussion of the lymph system will have to wait for another program.
Lymphocytes target different types of infections, and natural killers have the role of destroying body cells which have become infected.
Both red blood cells and white blood cells are manufactured in your bone marrow, which is the gooey stuff inside your largest bones. And boy, can it manufacture blood cells!
Your body manufactures 17 million red blood cells per second. If stress precipitates a need the body can produce up to 7 times that amount. Just to spell that out - that’s up to 119 million red blood cells per second!
So those are red and white blood cells. But more than half of your blood is actually plasma. Plasma is mostly water, but carries all sorts of important things around your body, including proteins, hormones, glucose and CO2.
One of the important roles of blood plasma is to carry the blood clotting agents around your body. It is very important that your blood remains liquid while it is circulating around your body. Clots inside the body can cause heart attacks, strokes and all sorts of other very serious problems.
On the other hand, if your skin gets cut, the blood comes out to clean and protect the site. But if it didn’t clot, it would simply continue to run outside your body until you had no blood left.
All of your blood vessels have a very thin inner layer called endothelium. If the endothelium is damaged it triggers changes in the platelets which are in your blood which begins the clotting process.
They then release a hormone which makes a kind of net, called fibrin, which covers the entire clot, and strengthens it. With the fibrin supporting the structure, other cells join in, including red and white blood cells.
This entire process stops the blood from flowing out of the body, and also grabs the sides of the cut and enables it to being healing.
And here is perhaps the most amazing part of all. Once the skin has healed, the body simply releases agents which completely dissolve the blood clot. If the clot were to remain in the body, it would cause untold damage. Because it can form so quickly, and then dissolve when it is no longer needed, the body is able to repair itself, often without even needing a Band-Aid.
Human blood has been studied in great detail, and we now know a lot about it. We can give blood transfusions, and do all sorts of other important things with blood.
But it wasn’t so long ago that it was all a bit of a mystery. Nobody really knew what blood was for. Doctors thought that most illness was caused by too much bad blood, and prescribed blood-letting for almost every ailment.
In fact, we didn’t even know that blood circulates around the body until the 1628. In that year, a doctor called William Harvey, who as a heavy coffee drinker, and thus always had lots of energy, published his book De Motu Cordis (in English that is “On the Motion of the Heart and Blood”)
One of Harvey’s techniques was to calculate the amount of blood in the body, and to measure the average heartbeat.
He found that an adult human has an average resting heart rate of about 75 beats per minute, the same rate as an adult sheep.
I guess it is obvious, but the bigger the animal, the slower the heartbeat. For example, a blue whale's heart is about the size of a compact car, and only beats five times per minute.
On the other hand, a shrew, which is a tiny animal, has a heart rate of about 1,000 beats per minute.
A couple more interesting and important facts about blood.
A fetus does not use its lungs while in utero. It derives its oxygen and nutrients from the mother via the umbilical cord. As a result the blood in a fetus circulates differently than once it is born. The blood flows into the right atrium of the heart, and there is a hole leading directly from there to the left atrium. As soon as the baby is born and takes its first breath, this hole in the heart closes up, and the blood begins circulating through the lungs, carrying oxygen to the body.
All of this happens in a few moments after the baby is born. Without this amazing feat, a baby would not survive for very long after birth.
Two final facts for you to consider. Every play by Shakespeare contains the word ‘blood’ at least once. And the word “Blood” appears in the Bible 354 times.
I guess blood really is important. And amazing. There is a blessing that is recited every day:
Blessed are You, Hashem our God, King of the universe, Who formed man with wisdom and created within him many openings and many hollows. It is obvious and known before Your Throne of Glory that if even one of them ruptures, or if even one of them becomes blocked, it would be impossible to survive and to stand before You. Blessed are You, Hashem, Who heals all flesh and acts wondrously.
We can truly appreciate how wondrous and amazing this really is. Our blood looks after us, and serves us so well. We should appreciate it every day.
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