It is the object of Yoga gradually to restrain the citta from its various states and thus cause it to turn back to its original cause, the kāraṇacitta, which is all-pervading. The modifications of the kāraṇacitta into such states as the kāryyacitta is due to its being overcome by its inherent tamas and rajas; so when the transformations of the citta into the passing states are arrested by concentration, there takes place a backward movement and the all-pervading state of the citta being restored to itself and all tamas being overcome, the Yogin acquires omniscience, and finally when this citta becomes as pure as the form of purusha itself, the purusha becomes conscious of himself and is liberated from the bonds of prakṛti. The Yoga philosophy in the first chapter describes the Yoga for him whose mind is inclined towards trance-cognition. In the second chapter is described the means by which one with an ordinary worldly mind (_vyutthāna citta_) may also acquire Yoga. In the third chapter are described those phenomena which strengthen the faith of the Yogin on the means of attaining Yoga described in the second chapter. In the fourth chapter is described kaivalya, absolute independence or oneness, which is the end of all the Yoga practices. The _Bhāshya_ describes the five classes of cittas and comments upon their fitness for the Yoga leading to kaivalya. Those are I. _kshipta_ (wandering), II. _mūḍha_ (forgetful), III. _vikshipta_ (occasionally steady), IV. _ekāgra_ (one-pointed), _niruddha_ (restrained). I. The _kshiptacitta_ is characterised as wandering, because it is being always moved by the rajas. This is that citta which is always moved to and fro by the rise of passions, the excess of which may indeed for the time overpower the mind and thus generate a temporary concentration, but it has nothing to do with the contemplative concentration required for attaining absolute independence. The man moved by rajas, far from attaining any mastery of himself, is rather a slave to his own passions and is always being moved to and fro and shaken by them (see _Siddhānta-candrikā_, I. 2, _Bhojavṛtti_, I. 2). II. The mūḍhacitta is that which is overpowered by tamas, or passions, like that of anger, etc., by which it loses its senses and always chooses the wrong course. Svāmin Hariharāraṇya suggests a beautiful example of such concentration as similar to that of certain snakes which become completely absorbed in the prey upon which they are about to pounce. III. The vikshiptacitta, or distracted or occasionally steady citta, is that mind which rationally avoids the painful actions and chooses the pleasurable ones. Now none of these three kinds of mind can hope to attain that contemplative concentration called Yoga. This last type of mind represents ordinary people, who sometimes tend towards good but relapse back to evil.