Despite being one of the first doctors to use observation and logical reasoning in his diagnoses, Hippocrates also believed that disease was caused by an imbalance of the four humours: blood, yellow bile, black bile and phlegm.


Hippocrates was one of the first to assert that diseases are not divine punishments or the result of demonic possessions, but have natural causes. This was a paradigm shift in the medicine of the time, which tended to attribute diseases to supernatural causes.


Although he is credited with many medical treatises and works, much of the writing attributed to Hippocrates was most likely written by a group of physicians who studied under his influence and are known as the Hippocratic school. This shows his great influence on medicine and his enduring legacy.