Mind is all-pervasive and can come in touch with the external world, by which we have the perception of the thing. Like light, which emits rays and pervades all, though it remains in one place, the citta by its vṛttis comes in contact with the external world, is changed into the form of the object of perception and thus becomes the cause of perception; as the citta has to pass through the senses, it becomes coloured by them, which explains the fact that perception is impossible without the help of the senses. As it has to pass through the senses, it undergoes the limitations of the senses, which it can avoid, if it can directly concentrate itself upon any object without the help of the senses; from this originates the prajñā, through which dawns absolute real knowledge of the thing; unhampered by the limitations of the senses which can act only within a certain area or distance and cannot cognize subtler objects.
We see that in ordinary perception our minds are drawn towards the object, as iron is attracted by magnets. Thus Bhikshu says in explaining Vyāsa-bhāshya IV. 17:—
“The objects of knowledge, though inactive in themselves, may yet draw the everchanging cittas towards them like a magnet and change them in accordance with their own forms, just as a piece of cloth is turned red by coming into contact with red lac.” So it is that the cittas attain the form of anything with which they come in touch and there is then the perception that that thing is known. Perception (pratyaksha) is distinguished from inference, etc., in this, that here the knowledge arrived at is predominantly of the specific and special characters (viśesha) of the thing and not of its generic qualities us in inference, etc.
Inference proceeds from inference, and depends upon the fact that certain common qualities are found in all the members of a class, as distinguished from the members of a different class. Thus the qualities affirmed of a class will be found to exist in all the individual members of that class; this attribution of the generic characters of a class to the individual members that come under it is the essence of inference.
An object perceived or inferred by a competent man is described by him in words with the intention of transferring his knowledge to another; and the mental modification, which has for its sphere the meaning of such words, is the verbal cognition of the hearer. When the speaker has neither perceived nor inferred the object, and speaks of things which cannot be believed, the authority of verbal cognition fails. But it does not fail in the original speaker, God or Īśvara, and his dictates the Śāstras with reference either to the object of perception or of inference.
Viparyyaya or unreal cognition is the knowledge of the unreal as in doubt—a knowledge which possesses a form that does not tally with the real nature of the thing either as doubt or as false knowledge. Doubt may be illustrated by taking the case of a man who sees something in dim light and doubts its nature. “Is it a wooden post or a man?” In nature there is either the wooden post or the man, but there is no such fact or entity which corresponds with doubt: “Is it a wooden post or a man?” Knowledge as doubt is not cognition of a fact or entity. The illusion of seeing all things yellow through a defect of the eye (as in jaundice) can only be corrected when the objects are seen in their true colours. In doubt, however, their defective nature is at once manifest. Thus when we cannot be sure whether a certain thing is a post or a man, we know that our knowledge is not definite. So we have not to wait till the illusoriness of the previous knowledge is demonstrated by the advent of right knowledge. The evil nature of viparyyaya is exemplified in avidyā nescience, asmitā, rāga, etc.[[45]]
Viparyyaya is distinguished from vikalpa—imagination—in this, that though the latter is also unreal knowledge its nature as such is not demonstrated by any knowledge that follows, but is on the contrary admitted on all sides by the common consent of mankind. But it is only the learned who can demonstrate by arguments the illusoriness of vikalpa or imagination.
All class notions and concepts are formed by taking note only of the general characters of things and associating them with a symbol called “name.” Things themselves, however, do not exist in the nature of these symbols or names or concepts; it is only an aspect of them that is diagrammatically represented by the intellect in the form of concepts. When concepts are united or separated in our thought and language, they consequently represent only an imaginary plane of knowledge, for the things are not as the concepts represent them. Thus when we say “Caitra’s cow,” it is only an imaginary relation for, strictly speaking, no such thing exists as the cow of Caitra. Caitra has no connection in reality with the cow. When we say purusha is of the nature of consciousness, there is the same illusory relation. Now what is here predicated of what? Purusha is consciousness itself, but in predication there must always be a statement of the relation of one to another. Thus it sometimes breaks a concept into two parts and predicates the one of the other, and sometimes predicates the unity of two concepts which are different. Thus its sphere has a wide latitude in all thought-process conducted through language and involves an element of abstraction and construction which is called vikalpa. This represents the faculty by which our concepts are arranged in an analytical or synthetical proposition. It is said to be śabdajñānānupāti vastuśūnyo vikalpaḥ, i.e. the knowledge that springs from relating concepts or names, which relating does not actually exist in the objective world as it is represented in propositional forms.
Sleep is that mental state which has for its objective substratum the feeling of emptiness. It is called a state or notion of mind, for it is called back on awakening; when we feel that we have slept well our minds are clear, when we have slept badly our minds are listless, wandering and unsteady. For a person who seeks to attain communion or samādhi, these desires of sleep are to be suppressed, like all other desires. Memory is the retaining in the mind of objects perceived when perception occurs by the union of the cittas with external objects, according to the forms of which the cittas are transformed; it retains these perceptions, as impressions or saṃskāras by means of its inherent tamas. These saṃskāras generate memory, when such events occur as can manifest them by virtue of associations.
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.