l knowledge which is only
abandoned under the influence of theory. We are instinctively willing to
believe that by due attention, more can be found in nature than that
which is observed at first sight. But we will not be content with less.
What we ask from the philosophy of science is some account of the
coherence of things perceptively known.

This means a refusal to countenance any theory of psychic additions to
the object known in perception. For example, what is given in perception
is the green grass. This is an object which we know as an ingredient in
nature. The theory of psychic additions would treat the greenness as a
psychic addition furnished by the perceiving mind, and would leave to
nature merely the molecules and the radiant energy which influence the
mind towards that perception. My argument is that this dragging in of
the mind as making additions of its own to the thing posited for
knowledge by sense-awareness is merely a way of shirking the problem of
natural philosophy. That problem is to discuss the relations _inter se_
of things known, abstracted from the bare fact that they are known.
Natural philosophy should never ask, what is in the mind and what is in
nature. To do so is a confession that it has failed to express relations
between things perceptively known, namely to express those natural
relations whose expression is natural philosophy. It may be that the
task is too hard for us, that the relations are too complex and too
various for our apprehension, or are too trivial to be worth the trouble
of exposition. It is indeed true that we have gone but a very small way
in the adequate formulation of such relations. But at least do not let
us endeavour to conceal failure under a theory of the byplay of the
perceiving mind.

What I am essentially protesting against is the bifurcation of nature
into two systems of reality, which, in so far as they are real, are real
in different senses. One reality would be the entities such as electrons
which are the study of speculative physics. This would be the reality
which is there for knowledge; although on this theory it is never known.
For what is known is the other sort of reality, which is the byplay of
the mind. Thus there would be two natures, one is the conjecture and the
other is the dream.

Another way of phrasing this theory which I am arguing against is to
bifurcate nature into two divisions, namely into the nature apprehended
in awareness and the n