25]" and the Samyutta-Nikaya puts into the
Buddha's mouth the following dogmatic statement[426]. "Consciousness
arises because of duality. What is that duality? Visual[427]
consciousness arises because of sight and because of visible objects.
Sight is transitory and mutable: it is its very nature to change.
Visible objects are the same. So this duality is both in movement and
transitory."

The question of the reality of the external world did not present itself
to the early Buddhists. Had it been posed we may surmise that the Buddha
would have replied, as in similar cases, that the question was not
properly put. He would not, we may imagine, have admitted that the human
mind has the creative power which idealism postulates, for such power
seems to imply the existence of something like a self or atman. But
still though the Pitakas emphasize the empirical duality of sense-organs
and sense-objects, they also supply a basis for the doctrines of
Nagarjuna and Asanga, which like much late Buddhist metaphysics insist
on using logic in regions where the master would not use it. When it is
said that the genesis of the world and its passing away are within this
mortal frame, the meaning probably is that the world as we experience it
with its pains and pleasures depends on the senses and that with the
modification or cessation of the senses it is changed or comes to an
end. In other words (for this doctrine like most of the Buddha's
doctrines is at bottom ethical rather than metaphysical) the saint can
make or unmake his own world and triumph over pain. But the theory of
sensation may be treated not ethically but metaphysically. Sensation
implies a duality and on the one side the Buddha's teaching argues that
there is no permanent sentient self but merely different kinds of
consciousness arising in response to different stimuli. It is admitted
too that visible objects are changing and transitory like sight itself
and thus there is no reason to regard the external world, which is one
half of the duality, as more permanent, self-existent and continuous
than the other half. When we apply to it the destructive analysis which
the Buddha applied only to mental states, we easily arrive at the
nihilism or idealism of the later Buddhists. Of this I will treat later.
For the present we have only to note that early Buddhism holds that
sensation depends on contact, that is on a duality. It does not
investigate the external part of this dualit