The yoga philosophy, while it treats of a variety of subjects, is necessarily a congeries of many sciences in itself. It is the Hindu form of metaphysical argument for the existence of the ‘One Eternal’—the Platonic “Reality.” It is ontology in as much as it teaches _a priori_ the being of God. It is psychology in its treatment of the doctrine of feelings and passions, and it is morality in teaching us to keep them under control as brutal propensities, for the sake of securing our final emancipation and ultimate restoration into the spirit of spirits. Thus it partakes of the nature of many sciences in treating of the particular subject of divinity. The Yoga in its widest sense of the application of the mind to any subject is both practical, called _kriyá Yoga_, as also theoretical, known as _Jnána Yoga_; and includes in itself the two processes of synthesis and analysis alike, in its combination (_Yoga_) of things together, and discrimination (_Viveka_) of one from the other, in its inquiry into the nature of things (_Vastuvichára_), and investigation of their abstract essence called _Satyánusandhánná_. It uses both the _a priori_ (_púrvavat_) and _a posteriori_ (_paravat_) arguments to prove the existence of the world from its Maker and the _vice versa_, as indicated in the two aphorisms of induction and deduction _Yatová imani_ and _Janmadyasya yatah &c._ It views both subjectively and objectively the one self in many and the many in one unto which all is to return, by the two mysterious formulas of _So ham_ and _tat twam &c._ It is the reunion of detached souls with the Supreme that is the chief object of the Yoga philosophy to effect by the aforesaid processes and other means, which we propose fully to elucidate in the following pages; and there is no soul we think so very reprobate, that will feel disinclined to take a deep interest in them, in order to effect its reunion with the main source of its being and the only fountain of all blessings. On the contrary we are led to believe from the revival of the yoga-cult with the spiritualists and theosophists of the present day under the teachings of Madame Blavatsky and the lectures of Col. Olcott, that the Indian public are beginning to appreciate the efficacy of Yoga meditation, and its practice gaining ground among the pious and educated men in this country.