I have no
doubt that the theories had been vaguely floating about before as
obvious suggestions of common sense; for nothing in thought is ever
completely new. But at that epoch they were systematised and made exact,
and their complete consequences were ruthlessly deduced. It is the
establishment of this procedure of taking the consequences seriously
which marks the real discovery of a theory. Systematic doctrines of
light and sound as being something proceeding from the emitting bodies
were definitely established, and in particular the connexion of light
with colour was laid bare by Newton.

The result completely destroyed the simplicity of the 'substance and
attribute' theory of perception. What we see depends on the light
entering the eye. Furthermore we do not even perceive what enters the
eye. The things transmitted are waves or--as Newton thought--minute
particles, and the things seen are colours. Locke met this difficulty by
a theory of primary and secondary qualities. Namely, there are some
attributes of the matter which we do perceive. These are the primary
qualities, and there are other things which we perceive, such as
colours, which are not attributes of matter, but are perceived by us as
if they were such attributes. These are the secondary qualities of
matter.

Why should we perceive secondary qualities? It seems an extremely
unfortunate arrangement that we should perceive a lot of things that are
not there. Yet this is what the theory of secondary qualities in fact
comes to. There is now reigning in philosophy and in science an
apathetic acquiescence in the conclusion that no coherent account can be
given of nature as it is disclosed to us in sense-awareness, without
dragging in its relations to mind. The modern account of nature is not,
as it should be, merely an account of what the mind knows of nature; but
it is also confused with an account of what nature does to the mind. The
result has been disastrous both to science and to philosophy, but
chiefly to philosophy. It has transformed the grand question of the
relations between nature and mind into the petty form of the interaction
between the human body and mind.

Berkeley's polemic against matter was based on this confusion introduced
by the transmission theory of light. He advocated, rightly as I think,
the abandonment of the doctrine of matter in its present form. He had
however nothing to put in its place except a theory of the relation of
fin