Seers and thinkers have wrestled with the apparent opposition between our sense of free will on the one side, and the seeming machinery of the universe with its fixed and inexorable rules on the other. This is not purely an intellectual or philosophical issue, but an important fundamental question of whether and to what extent it is possible to realise freedom from the mechanisms of the universe, as well as the next question of how to go about achieving this freedom.
The Sankhya philosophy provided one answer that has been quite influential in the direction taken in India by those who practice Yoga. Even if it does not perfectly answer all the questions of existence, it provides at least a practical basis for the yogic effort, and figures, therefore, prominently in texts such as the Bhagavad Gita.
Sri Aurobindo sums up the Sankhya view this way: “The Sankhya explanation is that our present existence is governed by a dual principle. Prakriti is inert without the contact of Purusha, acts only by a junction with it and then too by the fixed mechanism of her instruments and qualities; Purusha, passive and free apart from Prakriti, becomes by contact with her and sanction to her works subject to this mechanism, lives in her limitation of ego-sense and must get free by withdrawing the sanction and returning to its own proper principle.
Others have formulated the duality between soul and nature somewhat differently as Sri Aurobindo points out: “Another explanation that tallies with a certain part of our experience is that there is a dual being in us, the animal and material, or more widely the lower nature-bound, and the soul or spiritual being entangled by mind in the material existence or in world-nature, and freedom comes by escape from the entanglement, the soul returning to its native planes or the self or spirit to its pure existence. The perfection of the soul then is to be found not at all in, but beyond Nature.”
In each case, the solution provided by the past efforts comes down to a withdrawal and abandonment of Nature in order to achieve the freedom of the Soul.
Sri Aurobindo, The Synthesis of Yoga, Part Four: The Yoga of Self-Perfection, Chapter 16, The Divine Shakti, pp. 725-726