The theory of Health and Disease, as expounded in Hindu Medical Treatises, is easy to understand. A living creature is composed of the soul, mind, and body. In the language of Punarvasu, this trinity reset on union like three sticks standing with one another's support." The compound is called Purusha or Being. It is this compound or soul, mind, and body that is the subject matter of the Science of Life. The soul is regarded as immutable. It is incapable of being affected by anything. It is eternal. It is regarded as the witness, for it views all things without being affected by anything. The body, like all other material objects. has for its constituent elements the five primordial essences viz., earth, water, fire, air, and ether These exist in the shape of juices, blood, flesh, bones, adeps, marrow, semen, and ojas. United with the senses or the instruments by which the mind acts, the compound is called animate. Without them, it is inanimate.
Body and mind are the subjects to which Health and Disease are inhered. When the constituent ingredients of the body are in their normal condition, the body is said to be in Health. When the functions of the mind are in their normal condition, and mind is said to be in Health. When the normal condition of both the body and the mind is disturbed, the result is Disease.
"Of all diseases, physical and mental" (to use the language of Punarvasu), "the causes, in brief, are three, viz., adverse correlation, absence of correlation, and excessive correlation, of Time, Mind, and the objects of the senses." Time is of two kinds, viz., that which we divide into seasons, months, fortnights, weeks, days, etc, and that which is concerned with the age of man and which we divide into infancy, youth, manhood, and decrepitude. Time, mind, and the objects of the senses have relations with each other and one another. When the harmony of these relations is disturbed, the result is disease. A person in a certain season or a certain age may do that with impunity which in another season or another age may be productive of harm. In this case, there occurs an adverse correlation or excessive correlation between time and the objects of sense. The eye exists for seeing, and the car for hearing. If one, however, keeps one's eyes directed to gaudy or blazing colors for a long time, or hears loud and disagreeable noises for hours together, the result is an injury to the organs of sense. There happens in these cases, an excess of correlation between the eye or the car and its object. If, again one keeps one's eyes continually shut the result is a weakening of vision or an incapacity to bear the light. In such cases, there is what we say in m absence of correlation between the eye and its object, the mind by dwelling too long and too closely on a particular object, may become deranged. This would be called an instance of excess of correlation between the mind and object. Thus, in respect of time, of mind, and the objects of the senses, excess of correlation, or the entire absence of correlation, or adverse correlation, are causes of disease both mental and bodily Fault of judgment or understanding is the sole cause of these abnormal correlations soundness of the understanding keeps them at a distance.