We have already seen that the indefinite ajnana could be experienced in direct perception and according to Vedanta there are only two categories. The category of the real, the self-luminous Brahman, and the category of the indefinite. The latter has for its ground the world-appearance, and is the principle by which the one unchangeable Brahman is falsely manifested in all the diversity of the manifold world. But this indefinite which is different from the category of the positive and the negative, has only a relative existence and will ultimately vanish, when the true knowledge of the Brahman dawns. Nothing however can be known about the nature of this indefinite except its character as indefinite. That all the phenomena of the world, the fixed order of events, the infinite variety of world-forms and names, all these are originated by this avidya, ajnana or maya is indeed hardly comprehensible. If it is indefinite nescience, how can all these well-defined forms of world-existence come out of it? It is said to exist only relatively, and to have only a temporary existence beside the permanent infinite reality. To take such a principle and to derive from it the mind, matter, and indeed everything else except the pure self-luminous Brahman, would hardly appeal to our reason. If this system of world-order were only seeming appearance, with no other element of truth in it except pure being, then it would be indefensible in the light of reason. It has been proved that whatever notions we have about the objective world are all self-contradictory, and thus groundless and false. If they have all proceeded from the indefinite they must show this character when exposed to discerning criticism. All categories have to be shown to be so hopelessly confused and to be without any conceivable notion that though apparent before us yet they crumble into indefiniteness as soon as they are examined, and one cannot make such assertion about them as that they are or that they are not. Such negative criticisms of our fundamental notions about the world-order were undertaken by S'rihar@sa and his commentator and follower Citsukha. It is impossible within the limits of this chapter, to give a complete account of their criticisms of our various notions of reality. I shall give here, only one example.
Let us take the examination of the notion of difference (_bheda_)from _Kha@n@danakha@n@dakhadya_. Four explanations are possible about the notion of difference: (1) the difference may be perceived as appearing in its own characteristics in our experience (_svarupa-bheda_) as Prabhakara thinks; (2) the difference between two things is nothing but the absence of one in the other (_anyonyabhava_), as some Naiyayikas and Bha@t@tas think; (3) difference means divergence of characteristics (_vaidharmya_) as the Vais'e@sikas speak of it; (4) difference may be a separate quality in itself like the p@rthaktva quality of Nyaya. Taking the first alternative, we see that it is said that the jug and the cloth represent in themselves, by their very form and existence, their mutual difference from each other. But if by perceiving the cloth we only perceive its difference from the jug as the characteristic of the cloth, then the jug also must have penetrated into the form of the cloth, otherwise how could we perceive in the cloth its characteristics as the difference from the jug? i.e. if difference is a thing which can be directly perceived by the senses, then as difference would naturally mean difference from something else, it is expected that something else such as jug, etc. from which the difference is perceived, must also be perceived directly in the perception of the cloth. But if the perception of "difference" between two things has penetrated together in the same identical perception, then the self-contradiction becomes apparent. Difference as an entity is not what we perceive in the cloth, for difference means difference from something else, and if that thing from which the difference is perceived is not perceived, then how can the difference as an entity be perceived? If it is said that the cloth itself represents its difference from the jug, and that this is indicated by the jug, then we may ask, what is the nature of the jug? If the difference from the cloth is the very nature of the jug, then the cloth itself is also involved in the nature of the jug. If it is said that the jug only indicates a term from which difference is intended to be conveyed, then that also becomes impossible, for how can we imagine that there is a term which is independent of any association of its difference from other things, and is yet a term which establishes the notion of difference? If it is a term of difference, it cannot be independent of its relation to other things from which it is differentiated. If its difference from the cloth is a quality of the jug, then also the old difficulty comes in, for its difference from the cloth would involve the cloth also in itself; and if the cloth is involved in the nature of the jug as its quality, then by the same manner the jug would also be the character of the cloth, and hence not difference but identity results. Moreover, if a cloth is perceived as a character of the jug, the two will appear to be hanging one over the other, but this is never so experienced by us. Moreover, it is difficult to ascertain if qualities have any relation with things; if they have not, then absence of relation being the same everywhere, everything might be the quality of everything. If there is a relation between these two, then that relation would require another relation to relate itself with that relation, and that would again require another relation and that another, and so on. Again, it may be said that when the jug, etc. are seen without reference to other things, they appear as jug, etc., but when they are viewed with reference to cloth, etc. they appear as difference. But this cannot be so, for the perception as jug is entirely different from the perception of difference. It should also be noted that the notion of difference is also different from the notions of both the jug and the cloth. It is one thing to say that there are jug and cloth, and quite another thing to say that the jug is different from the cloth. Thus a jug cannot appear as difference, though it may be viewed with reference to cloth. The notion of a jug does not require the notions of other things for its manifestation. Moreover, when I say the jug is different from the cloth, I never mean that difference is an entity which is the same as the jug or the cloth; what I mean is that the difference of the cloth from the jug has its limits in the jug, and not merely that the notion of cloth has a reference to jug. This shows that difference cannot be the characteristic nature of the thing perceived.
Again, in the second alternative where difference of two things is defined as the absence of each thing in the other, we find that if difference in jug and cloth means that the jug is not in the cloth or that cloth is not in jug, then also the same difficulty arises; for when I say that the absence or negation of jug in the cloth is its difference from the jug, then also the residence of the absence of jug in the cloth would require that the jug also resides in the cloth, and this would reduce difference to identity. If it is said that the absence of jug in the cloth is not a separate thing, but is rather the identical cloth itself, then also their difference as mutual exclusion cannot be explained. If this mutual negation (_anyonyabhava_) is explained as the mere absence of jugness in the cloth and of clothness in the jug, then also a difficulty arises; for there is no such quality in jugness or clothness that they may be mutually excluded; and there is no such quality in them that they can be treated as identical, and so when it is said that there is no jugness in cloth we might as well say that there is no clothness in cloth, for clothness and jugness are one and the same, and hence absence of jugness in the cloth would amount to the absence of clothness in the cloth which is self-contradictory. Taking again the third alternative we see that if difference means divergence of characteristics (_vaidharmya_), then the question arises whether the vaidharmya or divergence as existing in jug has such a divergence as can distinguish it from the divergence existing in the cloth; if the answer is in the affirmative then we require a series of endless vaidharmyas progressing _ad infinitum_. If the answer is in the negative then there being no divergence between the two divergences they become identical, and hence divergence of characteristics as such ceases to exist. If it is said that the natural forms of things are difference in themselves, for each of them excludes the other, then apart from the differences--the natural forms--the things are reduced to formlessness (_ni@hsvarupata_). If natural forms (_svarupa_) mean special natural forms (_svarupa-vis'e@sa_) then as the special natural forms or characteristics only represent difference, the natural forms of the things as apart from the special ones would appear to be identical. So also it may be proved that there is no such quality as p@rthaktva (separateness) which can explain differences of things, for there also the questions would arise as to whether separateness exists in different things or similar ones or whether separateness is identical with the thing in which it exists or not, and so forth.
The earliest beginnings of this method of subtle analysis and dialectic in Indian philosophy are found in the opening chapters of _Kathavatthu_. In the great _Mahabha@sya_ on Pa@nini by Patanjali also we find some traces of it. But Nagarjuna was the man who took it up in right earnest and systematically cultivated it in all its subtle and abstruse issues and counter-issues in order to prove that everything that appeared as a fixed order or system was non-existent, for all were unspeakable, indescribable and self-contradictory, and thus everything being discarded there was only the void (_s'unya_). S'a@nkara partially utilized this method in his refutations of Nyaya and the Buddhist systems; but S'rihar@sa again revived and developed it in a striking manner, and after having criticized the most important notions and concepts of our everyday life, which are often backed by the Nyaya system, sought to prove that nothing in the world can be defined, and that we cannot ascertain whether a thing is or is not. The refutations of all possible definitions that the Nyaya could give necessarily led to the conclusion that the things sought to be defined did not exist though they appeared to do so; the Vedantic contention was that this is exactly as it should be, for the indefinite ajnana produces only appearances which when exposed to reason show that no consistent notions of them can be formed, or in other words the world-appearance, the phenomena of maya or ajnana, are indefinable or anirvacaniya. This great work of S'rihar@sa was followed by _Tattvadipika_ of Citsukha, in which he generally followed S'rihar@sa and sometimes supplemented him with the addition of criticisms of certain new concepts. The method of Vedanta thus followed on one side the method of S'unyavada in annulling all the concepts of world-appearance and on the other Vijnanavada Buddhism in proving the self-illuminating character of knowledge and ultimately established the self as the only self-luminous ultimate reality.