The Philosophy of Yoga
It is said that the original propounder of classical Yoga was Hiranyagarbha Himself. It is Patanjali Maharishi who formulated this science into a definite system under the name of Ashtanga Yoga or Raja Yoga. This forms one of the Shad-Darsananas or Classical Systems of Philosophy. Vyasa has explained the original aphorisms or Yoga Sutras of Patanjali and this has been further elaborated through a gloss by a learned author named Vachaspati Mishra, and through the celebrated writings of Vijnana Bhikshu.
The Yoga, in allegiance to the Sankhya, holds that there is an eternal and omnipresent inert Prakriti and a plurality of omnipresent Conscious Purusha. The Yoga accepts a third principle, viz., Ishvara. The contact of the Purusha with Prakriti makes the latter evolve itself into its various effects. The Purusha, due to Aviveka (non-discrimination), feels that it is an individual on account of its identification with Prakriti and its modifications.
The Yoga concerns itself with the method of freeing the Purusha from this bondage through right effort. Yoga is, thus, more a practical way of attainment than a philosophical excursion into the realms of the Spirit. As a Darsana, it is Sa-Ishvara Sankhya, i.e., it sanctions the twenty-five Tattvas of the Sankhya and adds one more, Ishvara. In doing so, Yoga fulfills its own characteristic of being an utterly practical system of Sadhana.
When covered over by the veil of ignorance (Aviveka), the Purusha imagines that He is imperfect, incomplete, and that fulfillment can be had only in His conjunction with Prakriti. The Purusha then, so to say, begins to gaze at Prakriti; and in the light of His consciousness, the inert Prakriti commences its kaleidoscopic display of objects. The Purusha, due to Prakriti-Samyoga, appears to desire for enjoyment of these objects. He acts, as it were. He seems to grasp the objects. Now bondage, though not essential to the Purusha, is complete and the vicious circle is kept up. Transmigration of the individual is the consequence of Aviveka and its effects. Yoga by its scientific processes cuts these three knots one by one and leads to Kaivalya Moksha which is the realization of the true Purusha as independent of Prakriti and its evolutes.
Deep within everyone there is an abiding faith in a Supreme Being, someone to whom a Sadhaka can look up for help and guidance, for protection and inspiration. But the ego does not allow this to happen. Disentanglement of the Purusha from the ego alone can lead to Its release from the snares of Prakriti. The ego can hardly be subdued by subjective analysis only; but it is easy to discriminate this ego as separate from the Purusha when it is voluntarily offered as a sacrifice at the altar of self-surrender to a Supreme Being, Ishvarapranidhana. This is the hypothesis of the Yoga, in addition to its exhortation to put forth effort (Sadhana-Marga).
Swami Sivananda Saraswati