The Vedanta philosophy looked at the constantly changing phenomena of the world-appearance and sought to discover the root whence proceeded the endless series of events and effects. The theory that effects were altogether new productions caused by the invariable unconditional and immediately preceding antecedents, as well as the theory that it was the cause which evolved and by its transformations produced the effect, are considered insufficient to explain the problem which the Vedanta had before it. Certain collocations invariably and unconditionally preceded certain effects, but this cannot explain how the previous set of phenomena could be regarded as producing the succeeding set. In fact the concept of causation and production had in it something quite undefinable and inexplicable. Our enquiry after the cause is an enquiry after a more fundamental and primary form of the truth of a thing than what appears at the present moment when we wished to know what was the cause of the jug, what we sought was a simpler form of which the effect was only a more complex form of manifestation, what is the ground, the root, out of which the effect has come forth? If apart from such an enquiry we take the pictorial representation of the causal phenomena in which some collocations being invariably present at an antecedent point of time, the effect springs forth into being, we find that we are just where we were before, and are unable to penetrate into the logic of the affair. The Nyaya definition of cause and effect may be of use to us in a general way in associating certain groups of things of a particular kind with certain other phenomena happening at a succeeding moment as being relevant pairs of which one being present the other also has a probability of being present, but can do nothing more than this. It does not answer our question as to the nature of cause. Antecedence in time is regarded in this view as an indispensable condition for the cause. But time, according to Nyaya, is one continuous entity; succession of time can only be conceived as antecedence and consequence of phenomena, and these again involve succession; thus the notions of succession of time and of the antecedence and consequence of time being mutually dependent upon each other (_anyonyas'raya_) neither of these can be conceived independently. Another important condition is invariability. But what does that mean? If it means invariable antecedence, then even an ass which is invariably present as an antecedent to the smoke rising from the washerman's house, must be regarded as the cause of the smoke [Footnote ref 587]. If it means such an antecedence as contributes to the happening of the effect, it becomes again difficult to understand anything about its contributingto the effect, for the only intelligible thing is the antecedence and nothing more. If invariability means the existence of that at the presence of which the effect comes into being, then also it fails, for there may be the seed but no shoot, for the mere presence of the seed will not suffice to produce the effect, the shoot. If it is said that a cause can produce an effect only when it is associated with its accessory factors, then also the question remains the same, for we have not understood what is meant by cause. Again when the same effect is often seen to be produced by a plurality of causes, the cause cannot be defined as that which happening the effect happens and failing the effect fails. It cannot also be said that in spite of the plurality of causes, each particular cause is so associated with its own particular kind of effect that from a special kind of cause we can without fail get a special kind of effect (cf. Vatsyayana and _Nyayamanjari_), for out of the same clay different effects come forth namely the jug, the plate, etc. Again if cause is defined as the collocation of factors, then the question arises as to what is meant by this collocation; does it mean the factors themselves or something else above them? On the former supposition the scattered factors being always present in the universe there should always be the effect; if it means something else above the specific factors, then that something always existing, there should always be the effect. Nor can collocation (_samagri_) be defined as the last movement of the causes immediately succeeding which the effect comes into being, for the relation of movement with the collocating cause is incomprehensible. Moreover if movement is defined as that which produces the effect, the very conception of causation which was required to be proved is taken for granted. The idea of necessity involved in the causal conception that a cause is that which must produce its effect is also equally undefinable, inexplicable, and logically inconceivable. Thus in whatsoever way we may seek to find out the real nature of the causal principle from the interminable series of cause-effect phenomena we fail. All the characteristics of the effects are indescribable and indefinable ajnana of maya, and in whatever way we may try to conceive these phenomena in themselves or in relation to one another we fail, for they are all carved out of the indefinite and are illogical and illusory, and some day will vanish for ever. The true cause is thus the pure being, the reality which is unshakable in itself, the ground upon which all appearances being imposed they appear as real. The true cause is thus the unchangeable being which persists through all experience, and the effect-phenomena are but impositions upon it of ajnana or avidya. It is thus the clay, the permanent, that is regarded as the cause of all clay-phenomena as jug, plates, etc. All the various modes in which the clay appears are mere appearances, unreal, indefinable and so illusory. The one truth is the clay. So in all world-phenomena the one truth is being, the Brahman, and all the phenomena that are being imposed on it are but illusory forms and names. This is what is called the _satkaryavada_ or more properly the _satkara@navada_ of the Vedanta, that the cause alone is true and ever existing, and phenomena in themselves are false. There is only this much truth in them, that all are imposed on the reality or being which alone is true. This appearance of the one cause the being, as the unreal many of the phenomena is what is called the _vivarttavada_ as distinguished from the _sa@mkhyayogapari@namavada_, in which the effect is regarded as the real development of the cause in its potential state. When the effect has a different kind of being from the cause it is called _vivartta_ but when the effect has the same kind of being as the cause it is called _pari@nama (kara@nasvalak@sa@nanyathabhava@h pari@nama@h tadvilak@sa@no vivartta@h_ or _vastunastatsamattako'nyathabhava@h pari@nama@h tadvi@samasattaka@h vivartta@h)_. Vedanta has as much to object against the Nyaya as against the pari@nama theory of causation of the Sa@mkhya; for movement, development, form, potentiality, and actuality--all these are indefinable and inconceivable in the light of reason; they cannot explain causation but only restate things and phenomena as they appear in the world. In reality however though phenomena are not identical with the cause, they can never be defined except in terms of the cause (_Tadabhedam vinaiva tadvyatireke@na durvacam karyyam vivartta@h)_.
This being the relation of cause and effect or Brahman and the world, the different followers of S'a@nkara Vedanta in explaining the cause of the world-appearance sometimes lay stress on the maya, ajnana or avidya, sometimes on the Brahman, and sometimes on them both. Thus Sarvaj@natmamuni, the writer of _Sa@nk@sepa-s'ariraka_ and his followers think that the pure Brahman should be regarded as the causal substance (_upadana_) of the world-appearance, whereas Prakas'atman Akhan@dananda, and Madhava hold that Brahman in association with maya, i.e. the maya-reflected form of Brahman as Is'vara should be regarded as the cause of the world-appearance. The world-appearance is an evolution or pari@nama of the maya as located in Is'vara, whereas Is'vara (God) is the vivartta causal matter. Others however make a distinction between maya as the cosmical factor of illusion and avidya as the manifestation of the same entity in the individual or jiva. They hold that though the world-appearance may be said to be produced by the maya yet the mind etc. associated with the individual are produced by the avidya with the jiva or the individual as the causal matter (_upadana_). Others hold that since it is the individual to whom both Is'vara and the world-appearance are manifested, it is better rather to think that these are all manifestations of the jiva in association with his avidya or ajnana. Others however hold that since in the world-appearance we find in one aspect pure being and in another materiality etc., both Brahman and maya are to be regarded as the cause, Brahman as the permanent causal matter, upadana and maya as the entity evolving in pari@nama. Vacaspati Mis'ra thinks that Brahman is the permanent cause of the world-appearance through maya as associated with jiva. Maya is thus only a sahakari or instrument as it were, by which the one Brahman appears in the eye of the jiva as the manifold world of appearance. Prakas'ananda holds however in his _Siddhanta Muktavali_ that Brahman itself is pure and absolutely unaffected even as illusory appearance, and is not even the causal matter of the world-appearance. Everything that we see in the phenomenal world, the whole field of world-appearance, is the product of maya, which is both the instrumental and the upadana (causal matter) of the world-illusion. But whatever these divergences of view may be, it is clear that they do not in any way affect the principal Vedanta text that the only unchangeable cause is the Brahman, whereas all else, the effect-phenomena, have only a temporary existence as indefinable illusion. The word maya was used in the @Rg-Veda in the sense of supernatural power and wonderful skill, and the idea of an inherent mystery underlying it was gradually emphasized in the Atharva Veda, and it began to be used in the sense of magic or illusion. In the B@rhadara@nyaka, Pras'na, and Svetas'vatara Upani@sads the word means magic. It is not out of place here to mention that in the older Upani@sads the word maya occurs only once in the B@rhadara@nyaka and once only in the Pras'na. In early Pali Buddhist writings it occurs only in the sense of deception or deceitful conduct. Buddhagho@sa uses it in the sense of magical power. In Nagarjuna and the _Lankavatara_ it has acquired the sense of illusion. In S'a@nkara the word maya is used in the sense of illusion, both as a principle of creation as a s'akti (power) or accessory cause, and as the phenomenal creation itself, as the illusion of world-appearance.
It may also be mentioned here that Gau@dapada the teacher of S'a@nkara's teacher Govinda worked out a system with the help of the maya doctrine. The Upani@sads are permeated with the spirit of an earnest enquiry after absolute truth. They do not pay any attention towards explaining the world-appearance or enquiring into its relations with absolute truth. Gau@dapada asserts clearly and probably for the first time among Hindu thinkers, that the world does not exist in reality, that it is maya, and not reality. When the highest truth is realized maya is not removed, for it is not a thing, but the whole world-illusion is dissolved into its own airy nothing never to recur again. It was Gau@dapada who compared the world-appearance with dream appearances, and held that objects seen in the waking world are unreal, because they are capable of being seen like objects seen in a dream, which are false and unreal. The atman says Gau@dapada is at once the cognizer and the cognized, the world subsists in the atman through maya. As atman alone is real and all duality an illusion, it necessarily follows that all experience is also illusory. S'a@nkara expounded this doctrine in his elaborate commentaries on the Upani@sads and the Brahma-sutra, but he seems to me to have done little more than making explicit the doctrine of maya. Some of his followers however examined and thought over the concept of maya and brought out in bold relief its character as the indefinable thereby substantially contributing to the development of the Vedanta philosophy.