Closely connected with the question as to the double nature of the
Brahman of the Upanishads is the question as to their teaching
Mâyâ.--From Colebrooke downwards the majority of European writers have
inclined towards the opinion that the doctrine of Mâyâ, i.e. of the
unreal illusory character of the sensible world, does not constitute a
feature of the primitive philosophy of the Upanishads, but was
introduced into the system at some later period, whether by Bâdarâya/n/a
or /S/a@nkara or somebody else. The opposite view, viz. that the
doctrine of Mâyâ forms an integral element of the teaching of the
Upanishads, is implied in them everywhere, and enunciated more or less
distinctly in more than one place, has in recent times been advocated
with much force by Mr. Gough in the ninth chapter of his Philosophy of
the Upanishads.

In his Matériaux, &c. M. Paul Régnaud remarks that 'the doctrine of
Mâyâ, although implied in the teaching of the Upanishads, could hardly
become clear and explicit before the system had reached a stage of
development necessitating a choice between admitting two co-existent
eternal principles (which became the basis of the Sâ@nkhya philosophy),
and accepting the predominance of the intellectual principle, which in
the end necessarily led to the negation of the opposite principle.'--To
the two alternatives here referred to as possible we, however, have to
add a third one, viz. that form of the Vedânta of which the theory of
the Bhâgavatas or Râmânujas is the most eminent type, and according to
which Brahman carries within its own nature an element from which the
material universe originates; an element which indeed is not an
independent entity like the pradhâna of the Sâ@nkhyas, but which at the
same time is not an unreal Mâyâ but quite as real as any other part of
Brahman's nature. That a doctrine of this character actually developed