As time passed, some of Galen's main theories were proved false. For example, Galen thought that the liver changed digested food into blood, which then flowed to the rest of the body and was absorbed. In 1628, however, the English physician William Harvey showed that blood circulates throughout the body and returns back to the heart.
Though Galen was proved wrong. He was the only doctor in ancient times to come up with a theory so close to the correct one. And his theories were very advanced for his age.
Galen discovered that the brain, not the heart, was the control centre of the body. He also figured out that the arteries were filled with blood not pneuma, which was what people believed it was filled with.
The three main Followings of Galen
1) Clinical Observation: -
The through observation of a patient’s symptoms and behaviour. The Doctor would later, note this down in a diary and would keep it in a shelf. This information would then be referred to, if any other cases with the same symptoms appeared.
Galen Followed Clinical observation very strongly. For he believed that if one can keep track of symptoms, they could tell at what time a disease comes more active and when it subdues.
2) The Four Humours: -
Galen was a fond believer in Hippocrates and his theories. The theory that he was most impressed by was the Four Humours. He later wrote other articles about the four humours in more detail, but these were lost in the destruction of the library at Alexandria.
3) Dissection: -
Galen believed in Dissection. The surgical opening of the human body for study. This however, was not allowed in Rome, for Christianity strongly disapproved of this practice. It was said in the bible that the body must be whole for the soul to leave in peace, to heaven. So, Galen had to be content with animals. He dissected pigs, cows, boars and other animals, and did an operation on a live pig, and by cutting nerves proved that many body functions are controlled by particular nerves.
Galen said “ This nerve controls the pigs speech, if I cut it, the pig cannot squeal.”
Galen cut the nerve, and the room waited for the squeal, but was never heard. The room was silent.
Galen was correct.
According to the facts that have been found, and the many that have been destroyed, I think we can safely conclude that Galen was one of the greatest doctors of the Ancient Times.
Galen's ideas dominated medicine throughout the middle Ages. He discovered that blood moved in the body, although he did not know that it circulated. Medical students studied his descriptions of operations, including a cure for breathing difficulties, long after his death. To help with the diagnosis of patients, Galen took their pulse, a practice that is still used today. Another interesting thing is that doctors studied Galen’s drawing of the heart until the 16th century.
