hough
inherent in nature, is comparatively superficial; and space and time are
each partial expressions of one fundamental relation between events
which is neither spatial nor temporal. This relation I call 'extension.'
The relation of 'extending over' is the relation of 'including,' either
in a spatial or in a temporal sense, or in both. But the mere
'inclusion' is more fundamental than either alternative and does not
require any spatio-temporal differentiation. In respect to extension two
events are mutually related so that either (i) one includes the other,
or (ii) one overlaps the other without complete inclusion, or (iii)
they are entirely separate. But great care is required in the
definition of spatial and temporal elements from this basis in order to
avoid tacit limitations really depending on undefined relations and
properties.

Such fallacies can be avoided by taking account of two elements in our
experience, namely, (i) our observational 'present,' and (ii) our
'percipient event.'

Our observational 'present' is what I call a 'duration.' It is the whole
of nature apprehended in our immediate observation. It has therefore the
nature of an event, but possesses a peculiar completeness which marks
out such durations as a special type of events inherent in nature. A
duration is not instantaneous. It is all that there is of nature with
certain temporal limitations. In contradistinction to other events a
duration will be called infinite and the other events are finite[10]. In
our knowledge of a duration we distinguish (i) certain included events
which are particularly discriminated as to their peculiar
individualities, and (ii) the remaining included events which are only
known as necessarily in being by reason of their relations to the
discriminated events and to the whole duration. The duration as a whole
is signified[11] by that quality of relatedness (in respect to
extension) possessed by the part which is immediately under observation;
namely, by the fact that there is essentially a beyond to whatever is
observed. I mean by this that every event is known as being related to
other events which it does not include. This fact, that every event is
known as possessing the quality of exclusion, shows that exclusion is as
positive a relation as inclusion. There are of course no merely
negative relations in nature, and exclusion is not the mere negative of
inclusion, though the two relations are contraries. Both rela