have
used for the purpose of illustration are the buildings of Bedford
College, Homer, and sky-blue. Evidently these are very different sorts
of things; and it is likely that statements which are made about one
kind of entity will not be true about other kinds. If human thought
proceeded with the orderly method which abstract logic would suggest to
it, we might go further and say that a classification of natural
entities should be the first step in science itself. Perhaps you will be
inclined to reply that this classification has already been effected,
and that science is concerned with the adventures of material entities
in space and time.

The history of the doctrine of matter has yet to be written. It is the
history of the influence of Greek philosophy on science. That influence
has issued in one long misconception of the metaphysical status of
natural entities. The entity has been separated from the factor which is
the terminus of sense-awareness. It has become the substratum for that
factor, and the factor has been degraded into an attribute of the
entity. In this way a distinction has been imported into nature which is
in truth no distinction at all. A natural entity is merely a factor of
fact, considered in itself. Its disconnexion from the complex of fact is
a mere abstraction. It is not the substratum of the factor, but the very
factor itself as bared in thought. Thus what is a mere procedure of mind
in the translation of sense-awareness into discursive knowledge has been
transmuted into a fundamental character of nature. In this way matter
has emerged as being the metaphysical substratum of its properties, and
the course of nature is interpreted as the history of matter.

Plato and Aristotle found Greek thought preoccupied with the quest for
the simple substances in terms of which the course of events could be
expressed. We may formulate this state of mind in the question, What is
nature made of? The answers which their genius gave to this question,
and more particularly the concepts which underlay the terms in which
they framed their answers, have determined the unquestioned
presuppositions as to time, space and matter which have reigned in
science.

In Plato the forms of thought are more fluid than in Aristotle, and
therefore, as I venture to think, the more valuable. Their importance
consists in the evidence they yield of cultivated thought about nature
before it had been forced into a uniform mould by t