Science is the father of knowledge, but opinion breeds ignorance. ~ Hippocrates
Hippocrates (~460–377 BCE) is considered the father of Western medicine. He is credited with being first to believe that diseases had natural causes rather than an infliction from the gods.
While an astute observer, Hippocrates often overreached in his conclusions, via supposition and bias – ironically ignoring his own dictum equating opinion with ignorance. Hippocrates thought that hysteria was restricted to women, believing it was due to the wanderings of the uterus. This misconception persisted until challenged by Sigmund Freud in the early 20th century.
In the late 5th century BCE, Empedocles explained the cosmos as comprising 4 elements, unchangeable in their intermingling: air, earth, water, and fire. He further proposed that the powers of love and strife variously stirred these elements into mixture and separation.
Taking his cue from Empedocles, Hippocrates presented a hypothesis of human humors in his treatise The Nature of Man. The classical elements formed the 4 basic bodily humors: blood, phlegm, black bile, and yellow bile.
According to Hippocrates, an imbalance or excess in a humor produces illness. When one has a cold, phlegm collects in the nose and throat. Bile is excreted from a serious wound. Blood flows when the skin is broken.
Hippocrates’ humors influenced the diagnosis and treatment of diseases for centuries. Bloodletting to vent a surfeit of blood was practiced well into the 19th century. The red-and-white barber’s pole originated as the sign of a bloodletter.
Hippocrates was also revolutionary in proposing natural causes for psychological problems. He formulated long-lasting theories of temperament and motivation.