अन्तःकरण, antaḥkaraṇa

The word antaḥkaraṇa (antaḥkaraṇ in Hindi) is consist of two: antar (inner, internal) and karaṇa (the means or instrument by which an action is effected). In Indian philosophy, antaḥkaraṇ is the unity of mental abilities, which are different, on one hand, from spiritual principle, on the other hand – from 10 indriyas.  

In Sankhya, antaḥkaraṇ includes 3 components: buddhi, ahamkara and manas.

According to Sankhya-karika, antaḥkaraṇ, in contrast to indriyas, which act only in the present tense, deals with objects of all three times. The indriyas themselves constitute object of antaḥkaraṇ and relate to it like doors with guards. Indriyas prepare cognitive material for antaḥkaraṇ, which it transmits (while manas and ahamkara are "subordinate" to buddhi) to Purusha (vv. 33, 35–36).

In Vedanta, antaḥkaraṇ includes, in addition to the three named principles, also chitta.

According to Shankara's “Tattvabodha”, it is the antaḥkaraṇ that is the “seat” of ignorance – avidya (v. 38). Antaḥkaraṇ itself also receives different localization: in Shankara's text, manas corresponds to throat, buddhi – to mouth, ahamkara – to heart, and chitta – to navel. Sureshvara, disciple of Shankara, places the entire antahkaran in the heart.

In Nath philosophy, antaḥkaraṇ includes five elements: manas, buddhi, ahamkara, chitta and chaitanya. Their properties and functions are listed by Gorakshanath in Siddha-siddhanta Paddhati. Antaḥkaraṇ is defined as sukshma-sharira of the individual soul, i.e. individualized spiritual self-manifestation of Supreme Spirit, Shiva.

For cognition of what antaḥkaraṇ is, it is necessary to get some spiritual experience, because it is not possible to cognize antahkaran with the help of mind, because mind (manas) itself is a part of antaḥkaraṇ system.

Antaḥkaraṇ is the link between spiritual and physical worlds, and is a tool for a higher spiritual experience for which one requires spiritual development.