Ācārya Pūjyapāda’s (circa 5th century CE) Samādhitantram is a spiritual work consisting of 105 verses outlining the path to liberation for the inspired soul.
Living beings have three kinds of soul – the extroverted-soul (bahirātmā), the introverted-soul (antarātmā), and the pure-soul (paramātmā). The one who mistakes the body and the like for the soul is the extroverted-soul (bahirātmā). The extroverted-soul spends his entire life in delusion and suffers throughout. The one who entertains no delusion about psychic dispositions – imperfections like attachment and aversion, and soul-nature – is the introverted-soul (antarātmā). The knowledgeable introverted-soul disconnects the body, including the senses, from the soul. The one who is utterly pure and rid of all karmic dirt is the pure-soul (paramātmā). Samādhitantram expounds the method of realizing the pure-soul, the light of supreme knowledge, and infinite bliss. Realization of the pure-soul is contingent upon discriminatory knowledge of the soul and the non-soul, and meditating incessantly on the pure-soul, rejecting everything that is non-soul. Samādhitantram answers the vexed question, ‘Who am I?’ in forceful and outrightly logical manner, in plain words. No one, the ascetic or the householder, can afford not to realize the Truth contained in the treatise, comprehend it through and through, and change his conduct accordingly.