The characters which science discerns in nature are subtle characters, not obvious at first sight.

They are relations of relations and characters of characters.

But for all their subtlety they are stamped with a certain simplicity which makes their consideration essential in unravelling the complex relations between characters of more perceptive insistence.
The fact that the bifurcation of nature into causal and apparent components does not express what we mean by our knowledge is brought before us when we realise our thoughts in any discussion of the causes of our perceptions.

For example, the fire is burning and we see a red coal.

This is explained in science by radiant energy from the coal entering our eyes.