The Antahkarana (Sanskrit: the inner cause), according to Hindu philosophy, refers to the totality of two levels of mind. The buddhi (higher mind), and the manas (middle levels of mind). According to The School for Esoteric Studies:
“This mental energy is made from three “lines of transmittal” the sutratma, the consciousness or Soul thread, and the creative thread. The sutratma is also known as the life thread; it is anchored in the heart and is withdrawn when the physical body dies. The consciousness thread is anchored in the physical brain and provides the flow of consciousness between the Soul and the personality. The creative thread is woven through our responses to life experiences; it is also referred to as “the Path.” “The Antahkarana is the product of the united effort of Soul and personality, working togetherconsciously to produce this bridge. When it is completed, there is a perfect rapport between the Monad and Its physical plane expression” (R&I:454-455).
The Antahkarana is developed in two stages. First, an energetic bridge of the intertwined threads is created between the integrated personality and the Soul. This portion of the Antahkarana is held within the ring-pass-not. The second part of the Antahkarana bridges initially from the Soul to the manasic permanent atom in the Spiritual Triad, thus moving beyond the ring-pass-not. Ultimately, the Antahkarana stretches directly between the integrated personality and the Monad, bypassing the Soul which is no longer needed.”
The Antahkarana also refers to a symbol used in the Reiki healing method.
To learn more about this symbol/concept, the video below provides a deeper look into the meaning of the Antahkarana.