We have just said that knowledge arises by itself and that it could not have been generated by sense-contact. If this be so, the diversity of perceptions is however left unexplained. But in face of the Nyaya philosophy explaining all perceptions on the ground of diverse sense-contact the Mima@msa probably could not afford to remain silent on such an important point. It therefore accepted the Nyaya view of sense-contact as a condition of knowledge with slight modifications, and yet held their doctrine of svata@h-prama@nya. It does not appear to have been conscious of a conflict between these two different principles of the production of knowledge. Evidently the point of view from which it looked at it was that the fact that there were the senses and contacts of them with the objects, or such special capacities in them by virtue of which the things could be perceived, was with us a matter of inference. Their actions in producing the knowledge are never experienced at the time of the rise of knowledge, but when the knowledge arises we argue that such and such senses must have acted. The only case where knowledge is found to be dependent on anything else seems to be the case where one knowledge is found to depend on a previous experience or knowledge as in the case of memory. In other cases the dependence of the rise of knowledge on anything else cannot be felt, for the physical collocations conditioning knowledge are not felt to be operating before the rise of knowledge, and these are only inferred later on in accordance with the nature and characteristic of knowledge. We always have our first start in knowledge which is directly experienced from which we may proceed later on to the operation and nature of objective facts in relation to it. Thus it is that though contact of the senses with the objects may later on be imagined to be the conditioning factor, yet the rise of knowledge as well as our notion of its validity strikes us as original, underived, immediate, and first-hand.
Prabhakara gives us a sketch as to how the existence of the senses may be inferred. Thus our cognitions of objects are phenomena which are not all the same, and do not happen always in the same manner, for these vary differently at different moments; the cognitions of course take place in the soul which may thus be regarded as the material cause (_samavayikara@na_); but there must be some such movements or other specific associations (_asamavayikara@na_) which render the production of this or that specific cognition possible. The immaterial causes subsist either in the cause of the material cause (e.g. in the case of the colouring of a white piece of cloth, the colour of the yarns which is the cause of the colour in the cloth subsists in the yarns which form the material cause of the cloth) or in the material cause itself (e.g. in the case of a new form of smell being produced in a substance by fire-contact, this contact, which is the immaterial cause of the smell, subsists in that substance itself which is put in the fire and in which the smell is produced). The soul is eternal and has no other cause, and it has to be assumed that the immaterial cause required for the rise of a cognition must inhere in the soul, and hence must be a quality. Then again accepting the Nyaya conclusions we know that the rise of qualities in an eternal thing can only take place by contact with some other substances. Now cognition being a quality which the soul acquires would naturally require the contact of such substances. Since there is nothing to show that such substances inhere in other substances they are also to be taken as eternal. There are three eternal substances, time, space, and atoms. But time and space being all-pervasive the soul is always in contact with them. Contact with these therefore cannot explain the occasional rise of different cognitions. This contact must then be of some kind of atom which resides in the body ensouled by the cognizing soul. This atom may be called _manas_ (mind). This manas alone by itself brings about cognitions, pleasure, pain, desire, aversion, effort, etc. The manas however by itself is found to be devoid of any such qualities as colour, smell, etc., and as such cannot lead the soul to experience or cognize these qualities; hence it stands in need of such other organs as may be characterized by these qualities; for the cognition of colour, the mind will need the aid of an organ of which colour is the characteristic quality; for the cognition of smell, an organ having the odorous characteristic and so on with touch, taste, vision. Now we know that the organ which has colour for its distinctive feature must be one composed of tejas or light, as colour is a feature of light, and this proves the existence of the organ, the eye--for the cognition of colour; in a similar manner the existence of the earthly organ (organ of smell), the aqueous organ (organ of taste), the akas'ic organ (organ of sound) and the airy organ (organ of touch) may be demonstrated. But without manas none of these organs is found to be effective. Four necessary contacts have to be admitted,
(1) of the sense organs with the object,
(2) of the sense organs with the qualities of the object,
(3) of the manas with the sense organs, and
(4) of the manas with the soul.
The objects of perception are of three kinds,
(1) substances,
(2) qualities,
(3) jati or class.
The material substances are tangible objects of earth, fire, water, air in large dimensions (for in their fine atomic states they cannot be perceived). The qualities are colour, taste, smell, touch, number, dimension, separateness, conjunction, disjunction, priority, posteriority, pleasure, pain, desire, aversion, and effort [Footnote ref 535].
It may not be out of place here to mention in conclusion that Kumarila Bha@t@ta was rather undecided as to the nature of the senses or of their contact with the objects. Thus he says that the senses may be conceived either as certain functions or activities, or as entities having the capacity of revealing things without coming into actual contact with them, or that they might be entities which actually come in contact with their objects [Footnote ref 536], and he prefers this last view as being more satisfactory.