In enquiring whether the Upanishads maintain the Maya doctrine or not, we must proceed with the same caution as regards other parts of the system, i.e. we must refrain from using unhesitatingly, and without careful consideration of the merits of each individual case, the teaching--direct or inferred--of any one passage to the end of determining the drift of the teaching of other passages. We may admit that some passages, notably of the B/ri/hadara/n/yaka, contain at any rate the germ of the later developed Maya doctrine[25], and thus render it quite intelligible that a system like /S/a@nkara's should evolve itself, among others, out of the Upanishads; but that affords no valid reason for interpreting Maya into other texts which give a very satisfactory sense without that doctrine, or are even clearly repugnant to it. This remark applies in the very first place to all the accounts of the creation of the physical universe. There, if anywhere, the illusional character of the world should have been hinted at, at least, had that theory been held by the authors of those accounts; but not a word to that effect is met with anywhere. The most important of those accounts--the one given in the sixth chapter of the Chandogya Upanishad--forms no exception. There is absolutely no reason to assume that the 'sending forth' of the elements from the primitive Sat, which is there described at length, was by the writer of that passage meant to represent a vivarta rather than a pari/n/ama that the process of the origination of the physical universe has to be conceived as anything else but a real manifestation of real powers hidden in the primeval Self. The introductory words, addressed to /S/vetaketu by Uddalaka, which are generally appealed to as intimating the unreal character of the evolution about to be described, do not, if viewed impartially, intimate any such thing[26]. For what is capable of being proved, and manifestly meant to be proved, by the illustrative instances of the lump of clay and the nugget of gold, through which there are known all things made of clay and gold? Merely that this whole world has Brahman for its causal substance, just as clay is the causal matter of every earthen pot, and gold of every golden ornament, but not that the process through which any causal substance becomes an effect is an unreal one. We--including Uddalaka--may surely say that all earthen pots are in reality nothing but earth--the earthen pot being merely a special modification (vikara) of clay which has a name of its own--without thereby committing ourselves to the doctrine that the change of form, which a lump of clay undergoes when being fashioned into a pot, is not real but a mere baseless illusion.