The fundamentals of the human personality or the body-mind complex are explained in Tattva Bodha (one of the preparatory texts by Adi Sankaracharya). These are technical terms that are important in understanding the teachings in the scriptures.
The human personality consists of three layers of bodies called śarīratrayam or dehatrayam. The three layers of the body are gross body (sthūla śarīram), subtle body (sūkṣma śarīram), and causal body (kāraṇa śarīram). In this analysis, the following four aspects of each body is discussed:
• The material with which each body is made up of
• The components of each body
• The functions of each body
• The nature of each body