Tatwa Bodha is an eloquent medical text, though it is seemingly spiritual in content. Where else can we see a description of the different parts of our being? While the medical texts do not go beyond the gross body we can see with our eyes, Sri Adi Sankaracharya goes a step more.
The student asks him what is the sukshma shareera or the subtle body? The question springs from an earlier answer for atma or the self. While the gross body is a combination of five elements which have gone through a process of Pancheekarana or a mathematical combination of five elements, the subtle body is made up of the five elements which have not gone through it.
The subtle body—a combination of the vital airs, mind and intellect—is also the result of good actions done in the past. The differences in the different human bodies we see, the differences in the nature and the quality of each one’s mind and intellect, the differences in the locations and times that people are born, have all their bearing on this one factor called sat karma or good deeds. The more good actions a person does, the better is the placement at the time of birth—a prosperous, learned or a beautiful and harmonious family. As the quality of the actions of an individual deteriorates, the circumstances of birth and the wealth of the surroundings one is born with also deteriorate.
The subtle body or something that is as if in the shape of the gross physical body is not visible to the eye, but can be experienced by the individual in the subtle body. It is the space for experiencing joy and sorrow, praise and censure. It is the experience of the five sense organs of perception—sound, sight, smell, taste and touch—and the five sense organs of action—speech, grasping with the hands, walking with the feet, the excretory and reproductive organs, the five vital movements of air in the form of perception; the energy with which we grasp forms through the eyes, sounds through the ears, smells, tastes and different experiences through the skin.
Together with the sense organs of perception and of action are the five vital airs of Prana (perception), Apana (expulsion), Samana (digestion), Vyana (circulation) and Udana (the force that raises and lifts up thoughts in the mind.
Then there is the mind and the intellect. The collective knowledge through the sense organs is the mind. The stimulus it receives is passed on to the intellect, which in turn gives directions to be executed through the organs of action. Our subtle body is constituted of these 17 aspects and even that is called ‘this’, and not I or You. The grammatical expression of etat shows that the subtle body is also inanimate matter.