400 B.C.-200 A.D.: A history of 'vital air'

Air has existed since the beginning of our existence, that we know for sure.  Without air we wouldn't have life, and people must have figured that out at an early date.  They also must have figured out early that breathing is necessary for life, considering when people stop breathing life ends.  (7, page 473)

Primitive people and ancient societies didn't know about air, let alone about oxygen. However, as far back as 1000 B.C., ancient Hindu physicians who wrote the Charaka and Sustrata recognized both the presence of the lungs and the 'prana vayu,' a substance in the air that many historians believe was oxygen. (5)

"Charaka (500 B.C.) mentions the head, the chest, the ears, the tongue, the mouth and the nose as the seat of 'prana vayu.'  Sustrata (1000 B.C) spoke of 'prana vayu' as flowing in the mouth. What else can this 'prana vayu' be identified with," said S.K. Jindal in his 2008 book, "Oxygen Therapy." (5)

Anaximenes of Miletus (585-525 B.C.) believed that air "was the primary principle," and he referred to it as the pneuma, or "the breath of life," said William Henry Osler, the father of modern medicine. He said the "pneuma was described by Anaximens as the "psychic force that animates the body and leaves it at death -- 'our soul being air, holds us together'" (9, pages 38-39)

Yet it was Empedocles (490-430 B.C.), a pre-Socratic Greek philosopher, who first conceived the idea that air contained a substance that was vital to life. He defined air as one of the four basic elements: air, water, earth and fire. Everything that we see is made up of these substances, and health of animals and humans was determined by the equilibrium of these four substances. (9, page 40)

He was also the first to describe respiration:

"As soon as that humidity, of which there is a great store on the first formation of the foetus, begins to be diminished, the air insinuating itself through the pores of the body succeeds it; after this the natural heat, by its tendency to make its escape, drives the air out, and when this natural heat enters the body again the air follows it afresh. The former of these actions is called Inspiration, and the latter Expiration."  (1, page 47-48)

He described how with the inspiration air entered into the body, and that it was circulated through the body by the "continuous motion" of the blood, and that it nourishes the heart and the mind.  Empedocles explained that the heart "nourished in the sea of blood which courses in two opposite directions: this is the lace where is found for the most part when men call Thought; for the blood round the heart is Thought in mankind." (2, page 186)

He also may have been the first to observe in the "faetus in utero" that "respiration commenced before birth."

Aristotle (384-322 B.C.), a Greek philosopher and student of Plato (and teacher to Alexander the Great), mentioned "air" as one of the essential elements of life.  He observed that air had weight when he wrote that "a bladder filled with air was heavier than an empty bladder." (6, page 19)

He did not know that there was a difference between arteries and veins, although he did know that both were filled with blood. He also knew that the heart was the key to "circulation" of the vital spirit.  He actually came up with the term vessels as he noted the vessels contained the blood as in a vase. The lungs inhaled the spirits and pneuma from the air from the trachea (which he referred to as the arteria because it contained air. Hippocrates also referred to the trachea as the arteria). (9, page 72)

Praxagoras of Athens (born 340 B.C.) believed that "pulsation was only in the arteries, and maintained that only the veins contained blood, and the arteries air," wrote Osler.  "As a rule the arteries are empty after death, and Praxagoras believed that they were filled with an aeriform fluid, a sort of pneuma, which was responsible for their pulsation."  He was among the first to study the pulse. (9, page 72)

Archimides (287-212 B.C.), a Greek mathematician and astronomer, wrote that "air is weighed in air." (6, page 19)

In the 3rd century B.C., Erasistratos (335-280 B.C.) of the School of Alexandria, in Egypt, recognized the relationship between air and blood and that air was essential for life to exist. Around 294 B.C. Erasistratos "taught that arteries carried blood to the various parts of the body; those vessels carried air and air only, and the blood was carried in the other vessels, the veins."  (7, page 473)

He also believed the heart contained no blood (8, page 94)  In fact, Osler explains, it was for this reason arteries got their name, as the term "artery" comes from the Greek term arteria, or air.  The trachea was referred to as the windpipe, or arteria tracheia, also known as "the rough air tube." (9, page 72)

Erasistratos contested that air contained a substance (a pneuma) that, once it entered the body, it was transformed into this "vital pneuma" that was essential for life.  This transformation was performed in the "left ventricle of the heart and, together with blood, results in heat, energy, and life.... a part of the vital pneuma enters the brain where it turns into 'psychic pneuma.'  This psychic pneuma processes sensory perceptions and renders possible understanding and knowledge."  (3, page 8)

Osler said that this "vital pneuma" was also the cause of the heart beat, "the source of innate heat of the body, and it maintained the processes of digestion and nutrition." It was sent to the brain where an animal spirit is formed, and this spirit was sent to the nerves of the body to give the person emotion and sensation and motion. Osler added that when we use the terms "high spirits" and "low spirits," these terms come from the views of Erasistratos and other ancient Greek philosophers.  (9, page 73)

By 70-160 A.D. Athenaeus of Cicilia opened what was called the "pneumatic school" of medicine that "flourished" for many years.  The pneumatic theory held that there was a pneuma in the air that was inhaled, transported to the heart by vessels, and then transported to the rest of the body by vessels.  This pneuma was therefore essential for good health and life, for maintaining a balance of the four humors by maintaining an appropriate level of heat and moisture. (2, page 291)

Aretaeus of Cappadocia (130-200 A.D.), a physician from ancient Greece, believed the heart was "the exciting cause or principle of respiration," according to Hamilton, "being seated in the centre of the lungs, which it inspires with a desire for fresh air. The lungs he did not believe to be susceptible of pain, from being composed of a loose sort of substance like wool; rough cartilaginous arteries, according to him, were dispersed throughout them; they were unprovided with muscles, and furnished only with some small and slender nerves, by means of which their motion was produced." (1, page 32)

Middle Ages diagram of Galen's concept of blood flow

Aelius (Claudius) Galenus (better known as Galen) (130-200 A.D.), was a famous Greco-Roman physician who studied the heart extensively.  Osler said he "studied particularly the movements of the heart, the actions of the valves, and the pulsatile forces in the arteries. He observed venous blood was darker, and believed it provided nutrition to the body. Arterial blood was thinner and brighter, and this was because it contained an abundance of "vital spirit," or vital air.  Arterial blood was warmed in the left ventricle, and this heat was sent to all the organs of the body.(9, page 80).

Galen also observed, as did Erasistratus, that the veins and arteries communicate by small pores and small vessels that allows for the mingling of spirits and blood. He did not, however, know the blood circulated, as he though it made it's way to the organs by small pores. However, some historians, including Osler, believe he was very close to figuring this out, and if given more time he probably would have. He did not see the heart as a pump, but as a fireplace, said Osler. (9, page 80)

He believed the purpose of the heart was to warm the blood; that it was nothing more than a heater.  He believed the left ventricle purified the blood and sent pure blood to the vital organs, such as the liver.  (7, page 473)

It should also be known that, according to Phillip Crampton in his 1839 "Outlines of the history of medicine," nothing remained of the writings of Erasistratos, so much of what we know about his anatomical discoveries comes from the writings of Galen. Crampton said that Galen described the views of Erasistratus of the passage of blood and air through the body this way:

According to him, the air passes from the lungs to the heart, which performs the functions of a smith's bellows, attracting the air by the dilatation of the left auricle; from the left auricle it passes by the arteries which contain air, or rather animal spirits, to every part of the body. The veins contain all the blood, and according to this supposition, fever and inflammation are the consequence of any portion of blood passing, by an error loci, from the veins into the arteries. (10, page 519)

Galen supported this view and added to it.  Crampton said it was Galen who was perhaps the first to describe human respiration:

Some notion of the state of experimental philosophy in the time of Galen, may be formed from the account which he gives of the experiment by which he Convinced the assembled physicians and philosophers of Rome, that air was contained within the cavity of the chest, between the lungs and the pleura costalis; he says he explained to them the manner in which the air passed from the lungs through the cribriform plate of the sethmoid bone into the ventricles of the brain, in which a true respiration was performed, the organ rising and falling in correspondence with the motions of the chest, and the air escaping through the sutures and the palate (10, page 520)

So Galen supported the views of Erasistratos and then expanded upon them. He agreed with Erasistratus that some pneuma in the air was inhaled, warmed in the heart, and sent to the body by a series of vessels and cannals and pores.  He also believed something of waste was exhaled.  He actually proved by experiments Erisistratos wrong when he asserted the arteries contained air not blood.  Galen proved arteries contained blood.  (7, page 473)(9, page 82)

Arthur John Brock, in the introduction of his 1916 translation of some of Galen's works, explained Galen's thoughts on how blood and air flowed through the body:

In his opinion, the great bulk of the blood travelled with a to-and-fro motion in the veins, while a little of it, mixed with inspired air, moved in the same way along the arteries; whereas we now know that all the blood goes outward by the arteries and returns by the veins; in either case blood is carried to the tissues by blood-vessels, and Galen's ideas of tissue nutrition were wonderfully sound. (10, page xxxvi)

He also explained that the "spongy flesh of the lungs acts upon the air we inhale converting it to a subtler product, pneuma.  This refined breath passes through very find 'pores' into branches of the pulmonary vein, and thence is 'attracted,' with blood, by the attractive faculty into the left ventricle of the heart, where it encounters more hot blood and becomes metamorphosed into life giving, i.e. 'vital' pneuma." As the pneuma is 'transported' to the various parts of the body it is further metamophosed.  (4, page 45)

"Why were there two sets of vessels for the same fluid?" Galen wondered.  And he speculated, as historian William Hamilton said that...

...the great vein (vena cava) was the great reservoir of the blood, while the aorta was the recipient of the spirits, and that, notwithstanding the proximity of the mouths of the veins and arteries to each other, the blood, during the continuance of health, did not enter the vessels in which the spirits flow; but, when this arrangement happens to be disturbed by any violence, that the blood forces its way into the arteries, and occasions more or less disorder of the system. The only use which he assigned to the process of respiration was to supply the arteries with air (what he referred to as vital air).

Yet this is all just speculation, and there were many theories as to what this 'vital air' contained.  Regardless, Galen was so well respected by the medical community that his theory grabbed a hold and held a prominent position in the minds of physicians for the next 1,900 years.  This theory held strong even when better wisdom became available.

References:

1. Hamilton, William, "A History of Medicine, Surgery and Anatomy," 1831, Vol. I, London, New Burlington
2.  Prioreschi, Plinio, "A History of Medicine: Greek Medicine," Vol. II, 1994, 2004, 2nd ed., NE,  Horatius Press
3. Tesak, Juergen, Chris Code, "The History of Aphasia: Theories and Protagonists," 2008, New York, Psychology Press
4. Wilson, Nigel, "Encyclopedia of Ancient Greece," 2006, NY, Taylor and Francis
5. Jindel, S.K.,Ritesh Agarwal, "Oxygen Therapy," 2009,2nd ed., Jaypee Brothers, pages 5-8
6. Tissier, page 19
7. Hill, Leonard, "Recent Advances in Physiology and bio-chemistry," 1908, London, Edward Arnold
8. Garrison, Fielding H, "An introduction to the history of medicine," 3rd edition, 1922, Philadelphia and London, W.B. Saunders Company, page 95
9. Osler, William, "The Evolution of Modern Medicine: A series of lectures at Yale University on the Silliman Foundation in April, 1913," New Have, Yale University Press, 1921,
10. Crampton, Phillip, "Outlines of the history of medicine from the earliest historic period to the present time, intended to illustrate the connextion between the progress of anatomy and the improvements of the healing arts," read before the Royal College of Surgeons on November 29, 1838, published in The Dublin Journal of Medical Science, 1839, Volume 14, Dublin, Published by Hodges and Smith, pages 504-533
11. Galen, writer, Arthur John Brock, translator, "Galen: On the Natural Faculties," 1916, London and New York, William Hienemann and G.P. Putnam's Sons

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331 B.C- 619 A.D..: The School of Alexandria

Figure 1 --Alexander the Great had a vision of creating
a great city, and compiling all the science and wisdom of
the world in one place.  He died before he was 32, thus
not living to see his dream come true. 

The evolution of medicine was slow moving through most of history.  One of the reasons for this was that it was illegal to touch a human corpse except in preparing it for burial or cremation.  This was one of the main reasons Galen's ignorant explanations of the human body were worshiped as the medical Bible for over a thousand years after his death.  This created a roadblock for learning about diseases like asthma and allergies.

This roadblock made it so it was nearly impossible for there to be any major advancements in medicine.  If someone learned something about the human body by dissecting, it was usually done by stealing a corpse from a graveyard, or from a prison, and performed illegally.  And the information learned was kept secret from a monarchy that might kill you, or at least throw you in prison, for learning something that opposed the view of the establishment. So even if something was learned, it was probably never published.  And if it was published, it was so posthumously. 

Thankfully, however, there were a few places scattered around the world where it was legal to perform autopsies.  It was at these places where physicians would flock to obtain medical knowledge, and patients would flock to get the best treatment.  Among the first such place was the great city of Alexandria in Egypt. (1)

Alexander the Great is considered one of the greatest military leaders of all time.  Born in 356 B.C. in Macedonia, a city just north of Greece (Macedonia was not a city-state like Athens and Sparta).  He spent his childhood watching his father, Phillip II, build Greece into a great military power, winning battle after battle. (1)

When he was 13 Aristotle was hired to be his personal tutor.  Like other Greeks, he learned about science, medicine, and philosophy.  (1) Aristotle taught him to read and speak Greek, and taught him to respect philosophy the way the Greeks did.  He loved Greece, it's gods, it's history, and he dreamed of teaching it's culture to people all over the world. (2)

Figure 2 -- A rendering of Ancient Alexandria.  The lighthouse
you see depicted here was one of the seven wonders of the
ancient world.  This was one of the most beautiful cities ever.

His father, Phillip, conquered most of the Greek city-states, and when his father died, Alexander went on to conquer many nations, including Egypt.  As he did in other places he conquered, he championed Greek culture.

As noted by historian John Watson:  "The rapid extension of Grecian arms under Alexander the Great, lead to the diffusion of taste and learning among the surrounding nations.  Pergamus and the new capital of Egypt (Alexandria), became points of scientific attraction second only to Athens; and with the spread of general knowledge, the study of medicine extended to these cities."  (4, page 74)

The Asclepion of Pergamus was surrounded with architecturally amazing structures that "were occupied as places of public instruction and scientific intercourse. Here the orators, sophists, and philosophers of the city held their daily conferences, and sometimes amused themselves in expounding to the sick the vaticinations of the priests. As a school of medicine, the Asclepion of Pergamus enjoyed a long continued celebrity." (4, page 74)

Alexander died in 323 B.C. of a mysterious illness in the palace of Nebuchadrezzar II of Babylon.  He was only one month shy of his 32nd birthday.  At this time the Egyptian portion of Alexander's empire was given to Ptolomy Soter (367-282 B.C.), the brother of Alexander. 

Figure 3 -- The library of Alexandria was one of the largest libraries
in the ancient world.  Physicians came from all over the world
to study here.  Unfortunately it was destroyed by barbarians.
Can you just imagine if this was never destroyed?  Perhaps medical
knowledge would have been advanced faster, and there would be
better asthma and allergy knowledge today, and maybe even better
medicine, or a cure.  If I could go back in time, I'd want to go to the
City of Alexandria during its glory days and peruse ancient writings

Like Alexander, Ptolomy loved arts and sciences, and he formed the great library of Alexandria, and he placed Aristotle in charge of it.  (3, page 33) The flow of knowledge through this city was so abundant its great library "rendered Alexandria the great repository of science and wisdom." Some estimate that by the reign of Ptolomy Philadelphus (36-29 B.C.) the library had accumulated a collection "about two hundred thousand rolls of papyrus, equal to about ten thousand of our modern printed volumes." (4, page 79)

Ptolomy also started Museum of College of Philosophy, or the school of Alexandria, in 331 B.C., which was described best by John Watson in 1856:

It's chief apartment was a lecture room and place of general concourse.  Around the main building, on the outside, was a covered walk or portico.  And connected with it was an Exhedra, in which the philosophers sometimes sat in the open air... This noble institution was originally designed to serve in part as a school for the training of  youth in the higher walks of learning, and in part as a retreat within which men of genius and acquirements, free from the necessary and providing for their daily wants, might have leisure and opportunity, each in his own way, for extending the domain of science, or for increasing the enjoyments of improving the condition of their fellow beings. (4, pages 77-8)

Figure 4 -- Ptolomy

By the time of Ptolomy Philadelphus, the school "had already risen to the highest rank among the Greek schools. (4, page 79)

One of the main reasons for this was that for the first time in the ancient world, dissection was legal in Alexandria.  This was significant, because religion made even touching a human corpse illegal in Ancient Egypt, Greece and Rome.  Now, for the first time in history, the human body could be studied, and it was.  In this way Aristotle was able to describe the insides of the human body by actual dissection. (3, page 33)  

The school was also a place for public lectures and readings, which were very important in Alexandria, as in all ancient civilizations.  This was because books were expensive and few could read.  Great minds would orally educate about the common wisdom of the day, and readers, or orators, would "familiarize" people with the writings of Homer and other great authors of the day. (4, page 82) Watson explained:

Among the Greeks this had been the common mode of enlightening the people, of amusing them, and of molding their opinion.  Most of the poetry, and much of the written history of the nation, were prepared for public recitation.

Placed in charge of medicine at the school were Erasistratus and Herophilus.

Erasistratus (304-250 B.C.) was from the Isle of Chios, and was the grandson of Aristotle.  He was the founder of the school of anatomy at the school of Alexandria, performing many autopsies.  Herophilus (335-280 B.C.) was a native of Chalcedon and was educated at the school of Cos. He also performed many autopsies at the school. (4, page 85) 


Figure 5 -- Aristotle

Along with Aristotle, they both made stunning observations from their inspections of the internals of the human body, and postulated various hypothesis based on these observations.  For instance, Erasistratus discovered that the trachea was a passageway for air (pneuma) to the lungs, and he discovered veins and arteries both originate from the heart.  Only he, like Aristotle,  believed the arteries were filled with air not blood, and hence the name 'arteries.'  And the passage of pneuma from the veins to arteries was the cause of disease(3, page 35-6, 4, page 86))

He disregarded the four humors of Hippocrates and the four elements of Empedocles, and instead postulated that fevers were caused by inflammation.  He was not a believer in purgatives and most medicine, and instead preferred a good diet and gymnastics.  Some believe he was the first to recommend exercise as a means to stay healthy and for healing.  (4, page 86)

Herophilus was among the "first of the Hippocratic school to distinguish himself as an atomist."  He was the first to use the pulse as an "index of varying conditions of health and disease."(4, page 84)

He properly attributed the pulsations of the arteries to the heart. 




Figure 6 -- Herophilus

Of interest is that Herophilus was charged with opening "the bodies of living criminals, to discover the secret springs of life."  (3, page 35)

Unlike Erasistratus, he was a believer in the hypothesis that imbalances of the four humors cause most diseases.  (4, page 85)

He revered Hippocrates to the point that "when obliged to contradict him he always avoided mentioning his name."   Also, unlike his counterpart, he placed a "high value on drugs, which he called, 'the hands of the gods,' and used them in great variety.  (5, page 62-3)

Erasistratus was an empiracist.  Herophilus was a rationalist. In this way, "the same rivalry which existed in Greece between Cos and Cnidos arose also between Alexandria and Pergamus, in which later place Galen was born, and Aesculapius was held in great respect as one of its most celebrated divinities."  (3, page 36-37)

Regardless, anyone who wanted to be a physician in the ancient world was eager to learn at the school of medicine in Alexandria, as "to have studied medicine at Alexandria, was everywhere considered a passport to the confidence and patronage of the public."  (4, page 92)

The school continued "its celebrity as a seat of learning and as a school of medicine, until it was taken by Saracens in 638 of the Christian era."  (3, page 36)

Figure 7 -- 1532 woodcut showing Herophilus (L) and Erasistratus (R)

Alexandria would fall in 619 A.D., and that ended whatever medical wisdom came out of it.  Many of it's wonders were destroyed by barbarians, including it amazing library.  As the library went up in flames, so to did all medical wisdom except for random scrolls scattered here and there.  (6, page 150-2) (7, page 28)

Until the  School of Salerno was established in the 10th century, there were no known autopsies performed, and medicine was left in limbo, or what historians like to refer to as the dark ages of medicine.  (6, page 150-2) (7, page 28)

References:

1. "Alexander the Great Alexander of Macedon Biography: King of Macedonia and Conqueror of the Persian," historyofmacedonia.org, http://www.historyofmacedonia.org/AncientMacedonia/AlexandertheGreat.html
2. "Alexander the Great: Ancient Greece for kids," mrdonn.org, http://greece.mrdonn.org/alexander.html
3. Meryon, Edward, "History of Medicine: comprising a narrative of its progress from the earliest ages to the present and of the delusions incidental to its advance from empericism to the dignity of a science," volume I, London, 1861,
4. Watson, John, "The medical profession in ancient times," 1856, Baker and Godwin, New York
5. Withington, Edward Theodore, "Medical history from the earliest times,"
6. Garrison, Fielding Hudson, "An introduction to the history of medicine," 1922, Philadelphia, W.B. Saunders Company
7. The John Hopkins Hospital bulleton," (volume XV 1904), "From the epoch of the Alexandria School (300 B.C.)"

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