A Crotonean Pythagorean philosopher, physicist and doctor. He was taught personally but Pythagoras himself, and he is one of the few lucky that got to know the great master and have a close relationship with him. In order to show the limited view of human knowledge he points out early in his book that while Gods have a clear view of the visible and invisible world, people can only suppose and come to conclusions through their observations. It is obvious that in his long lost –except a few extracts- book, he wanted to talk about the visible world, rather than the invisible. As a result his ideas concerned the areas of medicine, physiology and psychology.
Alkmeon was the first to recognize the human brain as the main organ connecting all of the human senses. The difference between humans and animals is that while animals just fell, people can rationalize and understand.
His interest in medicine and physiology led him to express some remarkable ideas concerning health and sickness. He states that health, is harmony of the several forces affecting the body, the equality of rights inside the body of liquid, dry, hot, cold, bitter, sweet etc, but when one of them takes full control, sickness is born. Health is the symmetrical mixture of the different qualities inside us. The living body is a system where the basic forces that it consists of should be equal to their opposites and when that happens, the system works in harmony. Harmony is affected when a force gains power over her normal measures. Sickness is the disharmony created because of that. Healing as a result consists of balancing the disturbed equilibrium.
Alkmeon also tried to give a reasonable explanation of ageing and death of organisms. He explained the course of the body through the time, and towards death, as the consequence of a series of constant internal changes. Each living organism lives a linear course of life, not a circular one, but a straight line towards the end of death.
It is by similar case that he tried to prove the immortality of the soul. If the body is perished duo to his straight limited course, the celestial bodies are immortal because they move in a constant, eternal circle. Taking the sun as the best example of a seemingly endless circular eternal movement, we can understand Alkmeon’s teaching that the soul is immortal, moving constantly like the sun.