Thus matter represents the refusal to think away spatial and temporal characteristics and to arrive at the bare concept of an individual entity.

It is this refusal which has caused the muddle of importing the mere procedure of thought into the fact of nature.

The entity, bared of all characteristics except those of space and time, has acquired a physical status as the ultimate texture of nature; so that the course of nature is conceived as being merely the fortunes of matter in its adventure through space.
Thus the origin of the doctrine of matter is the outcome of uncritical acceptance of space and time as external conditions for natural existence.

By this I do not mean that any doubt should be thrown on facts of space and time as ingredients in nature.

What I do mean is 'the unconscious presupposition of space and time as being that within which nature is set.' This is exactly the sort of presupposition which tinges thought in any reaction against the subtlety of philosophical criticism.
My theory of the formation of the scientific doctrine of matter is that first philosophy illegitimately transformed the bare entity, which is simply an abstraction necessary for the method of thought, into the metaphysical substratum of these factors in nature which in various senses are assigned to entities as their attributes; and that, as a second step, scientists (including philosophers who were scientists) in conscious or unconscious ignoration of philosophy presupposed this substratum, _qua_ substratum for attributes, as nevertheless in time and space.
This is surely a muddle.