Abstract
It has been said that the tridosha theory in Ayurveda originated from the theory of the three elements of the universe. The names of these three doshas, which are roughly equivalent to humour, are vata (wind), pitta (bile),
and kapha (phlegm), corresponding to the three elements of the universe: air, fire, and water. On the other hand,
Buddhist medicine which has a close relation to Ayurveda is based on the theory of the four elements of the
universe which includes the earth as well as the three elements mentioned above. Greek medicine on the other
hand, is founded on the theory of the four humours, i. e. blood, yellow bile, black bile, and phlegm. Furthermore,
even in Ayurveda, like in "Sushruta Samhita", the theory of the four humours can be found: This includes the abovd-mentioned tridosha plus blood as the forth humour. "Timaios" by Plato also mentions this. We compared these various theories and pointed out that the tridosha theory had its origin in the theory of the four elements of the universe. The process of the formation of the tridosha theory is considered as follows:(1) "Earth" was segregated from the four elements of the universe owing to its solid properties, and was rearranged into the seven elments of the body called "dhatu"; and the other three elements, uwatern, "fire", and "air"，were integrated as the tridosha theory, namely, the theory of the three humours, owing to th&r properties of fluid; (2)"Blood", assigned to the element of "earth", was segregated from the tridosha because "blood" was considered to be comprised of the properties of every humour without having its own peculiar properties. Therefore, the diseases caused by deranged "blood" were regarded as an aggregate disease caused by the other three deranged humours. Then the category of the disease, caused by deranged "earth", did not appear.
