unique determination of the “interval” between two moments. The problem arising out of this is closely connected with the problem of space and time, and its solution is very important for physics. This solution i is, however, not necessary for the mere definition of space and time, and we will postpone it for a separate study, in which we propose to take up the problem of measuring continuous aggregates, with especial reference to time and space.
Space.—32. Moment is the name we have given to the sum of elements of experience which, for the observer who is the subject of this Experience, are simultaneous with a given element, or, in other words, with such an ideal part of a given Experience as will constitute the perceptual content of the mind in an inner instant. We chose the name moment in order better to distinguish between an instant of non-perceptual and an instant of perceptual experience. We speak of the parts of a given Experience, which come within the same moment, as being co-momentary. Between two co-momentary events there exists no relation of temporal sequence; a moment is thus nature as it would appear to a given mind in an instant, a section of nature in which there is no temporality. Such a section is, indeed, an abstraction which the mind can explore only in idea; reflexion upon it occupies a finite section of the inner time series, whereas the moment itself occupies no such finite section.
33. In the concept of moment the mind has not yet reached a reality which is not further reducible: a moment, too, can be found to be divisible into parts, and between its separate parts relations of order can be found to subsist. Proceeding along the path indicated in the foregoing section, we will postulate in every moment a relation which is applicable as between all parts of the moment: then this will be a formative relation, and the mode of ordering the elements of experience in a given moment we call the Form of this moment. Brief reflexion leads us to the conclusion that this relation, which exists between the co-momentary parts of experience, can be identified with the relation which we ordinarily call spatial. Momentary space can thus be defined as the sum of those ordering relations of a given moment which can be predicated as existing between any and all parts of this moment.
What this definition in effect says is that all events and all objects, with which physics has to do, occur in the space (that is, in spatial relations to the other parts) of some moment; taken together with the definition of time, it tells us that, through the mediation of this moment, they likewise
