The next two sheaths are the mano-maya and vijnana kosas. These constitute the antah-karana, which is four-fold-namely, the mind in its two-fold aspect of buddhi and manas, self-hood (ahamkara), and citta. (1) . The function of the first is doubt, samkalpa-vikalpatmaka, (uncertainty, certainty); of the second, determination (niscaya-karini); of the third (egoity), of the fourth consciousness (abhimana).
Manas automatically registers the facts which the senses perceive. Buddhi, on attending to such registration, discriminates, determines, and cognizes the object registered, which is set over and against the subjective self by Ahamkara. The function of citta is contemplation (cinta), the faculty (2) whereby the mind in its widest sense raises for itself the subject of its thought and dwells thereon. For whilst buddhi has but three moments in which it is born, exists, and dies, citta endures.
The antah-karana is master of the ten senses, which are the outer doors through which it looks forth upon the external world. The faculties, as opposed to the organs or instruments of sense, reside here. The centres of the powers inherent in the last two sheaths are in the Ajna Cakra and the region above this and below the sahasrara lotus. In the latter the Atma of the last sheath of bliss resides. The physical or gross body is called sthula-sarira. The subtle body (suksmasarira also called linga sarira and karana-sarira) comprises the ten indriyas, manas, ahamkara, buddhi, and the five functions of prana. This subtle body contains in itself the cause of rebirth into the gross body when the period of reincarnation arrives.
1. According to Samkhyakarika, citta is included in buddhi. The above is the Vedantic classification.
2. The most important from the point of view of worship on account of mantra-smarana, devata-smarana, etc.