The word Yoga which was formerly used in Vedic literature in the sense of the restraint of the senses is used by Patanjali in his _Yoga sutra_ in the sense of the partial or full restraint or steadying of the states of citta. Some sort of concentration may be brought about by violent passions, as when fighting against a mortal enemy, or even by an ignorant attachment or instinct. The citta which has the concentration of the former type is called _k@sipta_ (wild) and of the latter type _pramu@dha_ (ignorant). There is another kind of citta, as with all ordinary people, in which concentration is only possible for a time, the mind remaining steady on one thing for a short time leaves that off and clings to another thing and so on. This is called the _vik@sipta_ (unsteady) stage of mind (_cittabhumi_). As distinguished from these there is an advanced stage of citta in which it can concentrate steadily on an object for a long time. This is the _ekagra_ (one-pointed) stage. There is a still further advanced stage in which the citta processes are absolutely stopped. This happens immediately before mukti, and is called the _nirodha_ (cessation) state of citta. The purpose of Yoga is to achieve the conditions of the last two stages of citta.
The cittas have five processes (_v@rtti_), (1) _prama@na_ [Footnote ref 392]
(validcognitive states such as are generated by perception, inference and scriptural testimony), (2) _viparyaya_ (false knowledge, illusion, etc.), (3) _vikalpa_ (abstraction, construction and different kinds of imagination), (4) _nidra_ (sleep, is a vacant state of mind, in which tamas tends to predominate), (5) _sm@rti_ (memory).
These states of mind (_v@rtti_) comprise our inner experience. When they lead us towards sa@msara into the course of passions and their satisfactions, they are said to be _kli@s@ta_ (afflicted or leading to affliction); when they lead us towards liberation, they are called _akli@s@ta_ (unafflicted). To whichever side we go, towards sa@msara or towards mukti, we have to make use of our states of mind; the states which are bad often alternate with good states, and whichever state should tend towards our final good (liberation) must be regarded as good.
This draws attention to that important characteristic of citta, that it sometimes tends towards good (i.e. liberation) and sometimes towards bad (sa@msara). It is like a river, as the _Vyasabha@sya says, which flows both ways, towards sin and towards the good. The teleology of prak@rti requires that it should produce in man the sa@msara as well as the liberation tendency.
Thus in accordance with it in the midst of many bad thoughts and bad habits there come good moral will and good thoughts, and in the midst of good thoughts and habits come also bad thoughts and vicious tendencies. The will to be good is therefore never lost in man, as it is an innate tendency in him which is as strong as his desire to enjoy pleasures. This point is rather remarkable, for it gives us the key of Yoga ethics and shows that our desire of liberation is not actuated by any hedonistic attraction for happiness or even removal of pain, but by an innate tendency of the mind to follow the path of liberation [Footnote ref 393]. Removal of painsis of course the concomitant effect of following such a course, but still the motive to follow this path is a natural and irresistible tendency of the mind. Man has power (_s'akti_) stored up in his citta, and he has to use it in such a way that this tendency may gradually grow stronger and stronger and ultimately uproot the other. He must succeed in this, since prak@rti wants liberation for her final realization [Footnote ref 394].