One of the more interesting aspects that I always find when I am researching a historical period is the way medicine and the treatment of illness has changed over the years.
We like to think of progress as being a straight line, but when you examine the medical instruments of the beginning of the Roman Empire with those of the medieval times, it is quite clear that the Romans had greater skill.
Roman medicine reached its apogee under Galen. Marcus Aurelius described him as Rome's finest doctor. It has been postulated that it would have been far better to be under the care of Galen (AD 129 - AD 210) rather than any other physician almost to the closing years of the 19th century. Indeed, of all the Roman doctors, Galen's writing was the most copied, and he is the one doctor that we do have the greatest body work from.
But who was he?
Before becoming the emperor's private physician, Galen spent his early formative years, in the gladiatorial rings of Turkey--learning about wounds and the part diet played in recovery. Contrary to popular belief, the vast majority of gladiators did not fight to the death. He never discovered the circulation of blood, but was nearly there with his theory of blood ebbing and flowing. Because he was from a wealthy background, he was able to use patronage and commanded a far higher social position than most of other doctors in the Roman world. The reason he studied medicine than the more usual architecture or law was that when he was 17, his father received a sign that his son was destined to be a doctor.
Although he invoked Hippocrates in his writing, he did codify various theories. He felt fevers could be caused by several things--overheating through exposure to sun, certain types of exercise or indeed certain food and drink (e.g. hemp), the humours, or inflammation. Most doctors at the time thought fever had only one cause--the imbalance of humours.
Like many in the ancient world, he believed that first came diet, then drugs, venesection (letting of blood/other fluids) and finally surgery. He believed that a good doctor should also be a good cook. He also believed that good diet should be the first line of defense, along with sleep. And that the doctor had to match the treatment and the diet to the individual as every person had a different temperament. Thus he did not believe in indiscriminate blood letting.
If you are interested in read Galen's work, Galen on Food and Diet by Mark Grant translates Galen's work on food into English. There you can learn things like chickpeas are supposed to incite the need for sex and are suppose to increase the productive of sperm. This is why they were fed to stud horses. They are also supposed to break down kidney stones as they can have a purgative effect.
Galen's emphasis on diet also feeds into his stoic philosophy, and his belief that medicine was a legitimate branch of philosophy.
After Galen's death, the impetus to research and study the human body stagnated for a number of reasons--including the linking of medicine with philosophy. thus research into the human body and actual causes of ill health declined.