Literally meaning "enumeration ", it is a system of dualistic realism founded by sage Kapila , and closely related to Yoga . Yoga provides the practical techniques of liberation while Samkhya provides the metaphysical background .
The basic ideas of both are from an ancient pre vedic period , and they were later included in the list of the orthodox systems after they nominally accepted the authority of the Vedas .
Samkhya talks of two ultimate eternal realities - Spirit ( Purusa ) and Nature ( Prakrti). Prakrti is a single all pervasive unconscious complex substance which evolves the world into countless different shapes . Its three main constituents or elements are the Gunas , Sattva , Rajas ,and Tamas ( dealt with earlier ).
The unfolding of a new world occurs when Prakrti and Purusa associate , whereupon Prakrti begins to differentiate .Purusa is non matter or pure spirit , its mere presence activates Prakrti , but Purusa itself remains unchanged .
Samkhya originally lists twenty five tattvas or categories that make up the world .
The first twenty three emerge from Prakrti , the Purusa is the 24rth category and Prakrti is the 25th . Prakrti and Purusa are eternal .
Such a concept did not require a creator god so Samkhya was intially atheistic .Later under the influence of Yoga , a 26th tattva was added called Ishwara or God.
Basically there is only one Purusa , but when manifestation occurs it breaks up into numerous souls , some are liberated others are bound to bodies in nature and go through the cycle of rebirth , in human animal or other forms .
In essence the Spirit is always free , but when bound , it can be liberated from entanglement with matter only through knowledge , virtue , and the practice of Yoga .
The lack of knowledge of the distinction ( viveka) between Self and non Self , is the cause of suffering rooted in material existence .
When liberation is attained by spiritual training , the individual self ceases to be affected by life's vicissitudes and obeserves the world with dispassion . Liberation may be attained in this life ( Jivanmukti ) or inthe next world (Videhamukti). When finally released from the psycho physical organism ( including the intellect ) , the spirit remains eternally unconscious.