posits for immediate
discernment a certain whole, here called a 'duration'; thus a duration
is a definite natural entity. A duration is discriminated as a complex
of partial events, and the natural entities which are components of this
complex are thereby said to be 'simultaneous with this duration.' Also
in a derivative sense they are simultaneous with each other in respect
to this duration. Thus simultaneity is a definite natural relation. The
word 'duration' is perhaps unfortunate in so far as it suggests a mere
abstract stretch of time. This is not what I mean. A duration is a
concrete slab of nature limited by simultaneity which is an essential
factor disclosed in sense-awareness.

Nature is a process. As in the case of everything directly exhibited in
sense-awareness, there can be no explanation of this characteristic of
nature. All that can be done is to use language which may speculatively
demonstrate it, and also to express the relation of this factor in
nature to other factors.

It is an exhibition of the process of nature that each duration happens
and passes. The process of nature can also be termed the passage of
nature. I definitely refrain at this stage from using the word 'time,'
since the measurable time of science and of civilised life generally
merely exhibits some aspects of the more fundamental fact of the passage
of nature. I believe that in this doctrine I am in full accord with
Bergson, though he uses 'time' for the fundamental fact which I call the
'passage of nature.' Also the passage of nature is exhibited equally in
spatial transition as well as in temporal transition. It is in virtue of
its passage that nature is always moving on. It is involved in the
meaning of this property of 'moving on' that not only is any act of
sense-awareness just that act and no other, but the terminus of each act
is also unique and is the terminus of no other act. Sense-awareness
seizes its only chance and presents for knowledge something which is for
it alone.

There are two senses in which the terminus of sense-awareness is unique.
It is unique for the sense-awareness of an individual mind and it is
unique for the sense-awareness of all minds which are operating under
natural conditions. There is an important distinction between the two
cases. (i) For one mind not only is the discerned component of the
general fact exhibited in any act of sense-awareness distinct from the
discerned component of the general f