Thus memory comes when the percepts already known and acquired are kept in the mind in the form of impressions and are manifested by the udbodhakas or associative manifestors. It differs from perceptions in this that the latter are of the nature of perceiving the unknown and unperceived, whereas the former serves to bring before the mind percepts that have already been acquired. Memory is therefore of percepts already acquired by real cognition, unreal cognition, imagination, sleep and memory. It manifests itself in dreams as well as in waking states. The relation between these states of mind and the saṃskāras is this that their frequency and repetition strengthens the saṃskāras and thus ensures the revival of these states. They are all endowed with sukha (pleasure), duḥkha (pain) and moha (ignorance). These feelings cannot be treated separately from the states themselves, for their manifestations are not different from the manifestation of the states themselves. Knowledge and feeling are but two different aspects of the modifications of cittas derived from prakṛti; hence neither can be thought separately from the other. The fusion of feeling with knowledge is therefore here more fundamental than in the modern tripartite division of mind. In connection with this we are to consider the senses whose action on the external world is known as “perceiving,” “grahaṇa,” which is distinguished from “pratyaksha,” which means the effect of “perceiving,” viz. perception. Each sense has got its special sphere of work, e.g. sight is of the eye, and this is called their second aspect, viz. svarūpa. Their third aspect is of “asmitā” or ego, which manifests itself through the senses. Their fourth aspect is their characteristic of guṇas, viz. that of manifestation (_prakāśa_), action (_kriyā_) and retention (_sthiti_). Their fifth aspect is that they are set in motion for purusha, his experiences and liberation. It is indeed difficult to find the relation of manas with the senses and the cittas. In more than one place manas is identified with cittas, and, on the other hand, it is described as a sense organ. There is another aspect in which manas is said to be the king of the cognitive and motor senses. Looked at in this aspect, manas is possibly the directive side of the ego by which it guides the cognitive and conative senses in the external world and is the cause of their harmonious activity for the experience of purusha. As a necessary attribute of this directive character of manas, the power of concentration, which is developed by prāṇāyāma, is said to belong to manas. This is the rajas side of manas. There is another aspect of manas which is called the anuvyavasāya or reflection, by which the sensations (ālocana) are associated, differentiated, integrated, assimilated into percepts and concepts. This is possibly the sāttvika side of manas.