I simply draw attention to it here in order to point out that the wave-theory of light has not been adopted because waves are just the sort of things which ought to make a mind perceive colours.

This is no part of the evidence which has ever been adduced for the wave-theory, yet on the causal theory of perception, it is really the only relevant part.

In other words, science is not discussing the causes of knowledge, but the coherence of knowledge.

The understanding which is sought by science is an understanding of relations within nature.
So far I have discussed the bifurcation of nature in connexion with the theories of absolute time and of absolute space.

My reason has been that the introduction of the relational theories only weakens the case for bifurcation, and I wished to discuss this case on its strongest grounds.
For instance, suppose we adopt the relational theory of space.