Samkhya is the oldest among the philosophical systems and dates back to about 7c BC. Kapila, the author of `Samkhya Sutra", is considered to be the originator of this system. There are no purely Samkhya schools existing today in Hinduism, but its influence is felt in Yoga and Vedanta schools of philosophy. The Hindu yoga schools are sometimes referred to as the `Samkhya -yoga schools`.

According to Samkhya, the efficient cause of the world is Purusha and the material cause is Prakriti. Here Purusha stands for the `Supreme Self` and Prakriti stands for `Matter`. Purusha (Self) is the first principle of Samkhya. Prakriti is the second, the material principle of Samkhya.

The Samkhya system proposes the theory of evolution (prakriti-purusha) that is accepted by all other systems. The purusha (soul) of this system is unchanging and is a witness to the changes of prakriti. Hence the Samkhya system is based on dualism wherein nature (prakriti) and conscious spirit (purusha) are separate entities not derived from one another. Samkhya is essentially atheistic because it believes that the existence of god cannot be proved.

Samkhya, like all other systems of Indian philosophy, regards ignorance as the root cause of bondage and suffering. According to Samkhya, the Purusha is eternal, pure consciousness. Due to ignorance, it identifies itself with the physical body and its constituents - Manas, ahamkara(proud) and Mahat, which are products of Prakriti. Once it becomes free of this false identification and the material bonds, Moksha ensues.

Samkhya forms the philosophical basis for Yoga of Patanjali. Therefore, sometimes both Yoga and Samkhya can be grouped together, Yoga forming the practical methodology to achieve the goal, while Samkhya providing the rational analysis of the Truth.