which we will call a moment (analogously to the use of the term in photography). A moment will thus be the sum of elements of experience which are simultaneous with any element of experience, or, in other words, the sum of the elements of experience in a given instant. Perceptual Experience, then, ordered in accordance with the attributes of simultaneity and non-simultaneity, can be regarded as a one-dimensional continuum of moments, and physical time as an ordering principle, by which the moments in this continuum are ordered, a type of order, by which elements of experience are ordered in a one-dimensional continuum of moments.
30.1. It may be asked whether the conception of time or that of order is the more fundamental: I imagine that logically the latter, being the broader conception, is the more fundamental, but psychologically the former; psychologically, I think, the conception of order was derived from direct experience of (inner) time, which, as we have already indicated, is an inner, indisputable, and inevitable reality. There, I believe, we have also the reason for the psychological predominance of physical time over physical space, which we will define later: whereas logically both are merely variant types of order, psychologically the former is fixed far deeper in the constitution of the mind than the latter. Logically the relation of temporality is subordinate to the relation of order, as is evident from the fact that the fundamental relation “between,” while it is applicable to temporality, is applicable also to many other aspects of reality. Time is logically only a special instance of order where the relation “before-after” is expressed by the terms “earlier-later”.
31. I think, however, that I ought to emphasise again that our definition is in no way intended to solve the question as to the metaphysical character of time; our aim is to find a definition which, without any metaphysical preconception, will tell us what time is in the perceptions with which we have to do in physics and what properties we can ascribe to it in consequence. As far as our definition goes up to the present, we can already reject as devoid of meaning any view which would affirm any deformation or discontinuity of time. Time is not a continuum or aggregate of which we could possibly predicate these properties; time is a mode of ordering a given totality of our perceptions, and it is this totality which may be discontinuous, or may have certain metrical properties. Time of itself cannot have metrical properties; and when we speak of “measuring time,” it is merely a somewhat misleading name for the attempt to find in the continuum, in which we arrange our time percepts, a structure which will permit of a
