The question as to what kind of system is represented by the
Vedânta-sûtras may be approached in another way also. While hitherto we
have attempted to penetrate to the meaning of the Sûtras by means of the
different commentaries, we might try the opposite road, and, in the
first place, attempt to ascertain independently of the Sûtras what
doctrine is set forth in the Upanishads, whose teaching the Sûtras
doubtless aim at systematising. If, it might be urged, the Upanishads
can be convincingly shown to embody a certain settled doctrine, we must
consider it at the least highly probable that that very same
doctrine--of whatever special nature it may be--is hidden in the
enigmatical aphorisms of Bâdarâya/n/a.[24]

I do not, however, consider this line of argumentation a safe one. Even
if it could be shown that the teaching of all the chief Upanishads
agrees in all essential points (a subject to which some attention will
be paid later on), we should not on that account be entitled
unhesitatingly to assume that the Sûtras set forth the same doctrine.
Whatever the true philosophy of the Upanishads may be, there remains the
undeniable fact that there exist and have existed since very ancient
times not one but several essentially differing systems, all of which
lay claim to the distinction of being the true representatives of the
teaching of the Upanishads as well as of the Sûtras. Let us suppose, for
argument's sake, that, for instance, the doctrine of Mâyâ is distinctly
enunciated in the Upanishads; nevertheless Râmânuja and, for all we know
to the contrary, the whole series of more ancient commentators on whom
he looked as authorities in the interpretation of the Sûtras, denied
that the Upanishads teach Mâyâ, and it is hence by no means impossible
that Bâdarâya/n/a should have done the same. The à priori style of
reasoning as to the teaching of the Sûtras is therefore without much
force.