"The theory of the three humours is one of the fundamental principles of traditional medicine. As has been mentioned above, Ayurvedic theories draw an analogy with the universe, the physics of which serves as a model for an elementary physiology. Comparatively speaking, one may say that the bile (Thripa) corresponds to fire, the phelgm (Beken) to water and the air (Lung) to the wind of the universe. Each humour has its own function in this general system. - Air is responsible for respiration and bodily activity, speech and the mind. It controls blood circulation. It is dry and light. - Bile stimulates and appetite, is responsible for digestion and maintains the normal temperature of the body. It is also claimed to confer bravery and wisdom. It is intimately connected with blood and body temperature. It represents organic fire and is essentially active. It is hot. - Phlegm sustains the body and procures sleep. It is responsible for the movements of joints, muscle development, and confers patience. It is the aqueous element associated with bodily fluids. It is passive, cold and heavy. These three fundamental humours have complementary activities. When their respective quantities are not modified, they help to maintain a normal state. Good health is thus the result of a harmonious balance between these three humours. But this balance can also be slightly modifed in non-pathological proportions, depending on general criteria, such as the seasonal cycles for example, or particular criteria such as individual temperament. At the same time, the predominance of one or another can lead to imbalance and indispositions of various kinds, and results in sickness. The three humours are, therefore, both physiological elements of the body that are vital for its existence and potentially pathogenic elements. Various causes can trigger an imbalance in the three humours. These include eating habits, life-style, living conditions and environment. Under their influence, the humour can be aggravated and become a pathology. Spells cast by evil spirits and the consequences of one's own karma or bad actions from the past, are other triggering causes. The specific symptoms of these modifications in the humours are then, clearly apparent in the pulse, urine and on the surface of the body. In the event of sickness, pathological imbalances in the air, bile and phlegm are treated with antagonistic elements, namely drugs based respectively on earth, water and fire elements. Given the magical and religious aspects of certain disorders, prayer and virtuous practices may also be associated with conventional treatment".quoted from Ph.D. thesis Ajanta Mishra