sited for knowledge
by sense-awareness can be explained. It is impenetrable by thought, in
the sense that its peculiar essential character which enters into
experience by sense-awareness is for thought merely the guardian of its
individuality as a bare entity. Thus for thought 'red' is merely a
definite entity, though for awareness 'red' has the content of its
individuality. The transition from the 'red' of awareness to the 'red'
of thought is accompanied by a definite loss of content, namely by the
transition from the factor 'red' to the entity 'red.' This loss in the
transition to thought is compensated by the fact that thought is
communicable whereas sense-awareness is incommunicable.

Thus there are three components in our knowledge of nature, namely,
fact, factors, and entities. Fact is the undifferentiated terminus of
sense-awareness; factors are termini of sense-awareness, differentiated
as elements of fact; entities are factors in their function as the
termini of thought. The entities thus spoken of are natural entities.
Thought is wider than nature, so that there are entities for thought
which are not natural entities.

When we speak of nature as a complex of related entities, the 'complex'
is fact as an entity for thought, to whose bare individuality is
ascribed the property of embracing in its complexity the natural
entities. It is our business to analyse this conception and in the
course of the analysis space and time should appear. Evidently the
relations holding between natural entities are themselves natural
entities, namely they are also factors of fact, there for
sense-awareness. Accordingly the structure of the natural complex can
never be completed in thought, just as the factors of fact can never be
exhausted in sense-awareness. Unexhaustiveness is an essential character
of our knowledge of nature. Also nature does not exhaust the matter for
thought, namely there are thoughts which would not occur in any
homogeneous thinking about nature.

The question as to whether sense-perception involves thought is largely
verbal. If sense-perception involves a cognition of individuality
abstracted from the actual position of the entity as a factor in fact,
then it undoubtedly does involve thought. But if it is conceived as
sense-awareness of a factor in fact competent to evoke emotion and
purposeful action without further cognition, then it does not involve
thought. In such a case the terminus of the sense-aw