The Vayu, Pittam and Shleshma should be considered as the primary and the most essential factors in the constitution of human organism. These fundamental and vital humours, occupying respectively the lower, middle, and upper parts of the body, maintain its integrity. The human body is supported by the three fundamental humours in the same way as a dwelling house is propped up by three supporting poles or stays; from which fact, the body is called the three-supported one (Tristhunam) by certain authorities. A deranged condition of these three fundamental humours may bring about its dissolution or death, while on their continuance in a normal state depends the vitality of the organism. These three humours, in combination with a fourth, the principle of blood, determine the origin, preservation, and dissolution of animated organism and permeate it with their respective properties till the moment of death.
There can be no organism without Vayu, Pittam, Kapham and blood, which are necessary to constantly maintain its integrity. The terms Vata (Vayu), Pittam and Shleshma (Kapham) are respectively derived from the roots 'Va', to move or smell, 'Tapa,' to burn or to heat, and "Shlisha," to embrace, with the suffix 'Ta' thereto added. *
Now we shall describe the locations of the foregoing vital humours. The Vayu may be briefly described as located in the regions of the pelvis (Shroni), and the rectum (Guda). The Pittam has its seat in the region between the stomach (Amashaya) and the intestines (Pakvashaya) which is above the pelvis and the rectum and below the umbilicus, while the Kapham is ensconced within the cavity of the stomach (Amashaya.)
Now we shall divide the locations of each of the vital humours into five parts : - The five localities of the Vayu will be described under the head of Vata-Vyadhis nervous diseases), while those of Pittam are the liver and the spleen, the heart, the pupils of the eyes, the skin and the intestines (Pakvashaya. The Kapham is located in the region of the breast, the throat, the head, the joints and the stomach (Amashaya). The foregoing regions are the seats of the vital humours in their normal state.
* From this should be inferred that motion and smell arc the natural attributes of the vital Vayu, heal and burning are those of Pittam, and union and integration are those of Kapham.
The vital humours (Vayu, Pittam and Kapham maintain the integrity of the animated organism by creating, assimilating and diffusing strength in the same way as the moon, the sun, and the winds maintain the integrity of the terrestrial globe. *
Now it may be asked whether the Pittam is identical with the elemental fire, or is it something other than that? The question may be answered by stating that the Pittam is the same as fire. Since such symptoms, as a burning sensation, digestion (boiling, and all other characteristics of fire can never exhibit themselves in the human body without the intervention of Pittam. Pittam therefore is called internal fire.†
Consequently, an enfeebled action of Pittam is remedied by the administration of drugs and substances which are akin to the elemental fire in their attributes, while an abnormal or excessive action (secretion) of Pittam is subdued by cooling measures as an over-kindled fire is subdued by moisture. There is no other fire (heat making factor) in the organism than Pittam.
* The moon laves the earth and imparts to it the vitalising principle with her own ambrosial light. The sun draws off the moisture in virtue of his own attractive force, and the Vayu distributes the heat and moisture over its surface.
† The analogy is based on the healing (and metabolic) actions of Pittam, and does not extend to its liquid secretion (bile). But since the former attributes permeate in its entirely, it is designated the Internal fire.