puru@sa from prak@rti. This final purpose being attained the prak@rti can never again bind the purusa with reference to whom this right knowledge was generated; for other puru@sas however the bondage remains as before, and they continue their experiences from one birth to another in an endless cycle. Yoga, however, thinks that mere philosophy is not sufficient. In order to bring about liberation it is not enough that a true knowledge differentiating puru@sa and buddhi should arise, but it is necessary that all the old habits of experience of buddhi, all its samskaras should be once for all destroyed never to be revived again. At this stage the buddhi is transformed into its purest state, reflecting steadily the true nature of the puru@sa. This is the _kevala_ (oneness) state of existence after which (all sa@mskâras, all avidyâ being altogether uprooted) the citta is impotent any longer to hold on to the puru@sa, and like a stone hurled from a mountain top, gravitates back into the prak@rti [Footnote ref 1]. To destroy the old sa@mskâras, knowledge alone not being sufficient, a graduated course of practice is necessary. This graduated practice should be so arranged that by generating the practice of living higher and better modes of life, and steadying the mind on its subtler states, the habits of ordinary life may be removed. As the yogin advances he has to give up what he had adopted as good and try for that which is still better. Continuing thus he reaches the state when the buddhi is in its ultimate perfection and purity. At this stage the buddhi assumes the form of the puru@sa, and final liberation takes place. Karmas in Yoga are divided into four classes: (1) _s'ukla_ or white (_pu@nya_, those that produce happiness), (2) _k@r@s@na_ or black (_pâpa_, those that produce sorrow), (3) _s'ukla-k@r@s@na_ (_pu@nya-pâpa_, most of our ordinary actions are partly virtuous and partly vicious as they involve, if not anything else, at least the death of many insects), (4) _as'uklâk@r@s@na_ (those inner acts of self-abnegation, and meditation which are devoid of any fruits as pleasures or pains). All external actions involve some sins, for it is difficult to work in the world and avoid taking the lives of insects [Footnote ref 2]. All karmas ___________________________________________________________________ [Footnote 1: Both Sâ@mkhya and Yoga speak of this emancipated state a _Kaivalya_ (alone-ness), the former because all sorrows have been absolutely uprooted, never to grow up again and the latter because at this state puru@sa remains for ever alone without any association with buddhi, see _Sâ@mkhya kârikâ_, 68 and _Yoga sûtras_, IV. 34.] [Footnote 2: _Vyâsabhâ@sya_ and _Tattvavais'âradî_, IV. 7.] 267 proceed from the five-fold afflictions (_kles'as_), namely _avidyâ, asmitâ, râga, dve@sa_ and _abhinives'a_.