Process and Reality — the Gifford Lectures, 1929

The strain-loci in the present epoch seem to be confined to the contemporaries of their experient occasions. In fact ‘strain-loci’ occur as essential components for perception in the mode of presentational immediacy. In this mode of perception there is a unique strain-locus for each such experient. Rest and motion are definable by reference to real strain-loci, and to potential strain-loci. Thus the molecules, forming material bodies for which the science of dynamics is important, may be presumed to have unique strain-loci associated with their prehensions.

This recapitulation of the theories of durations and strain-loci brings out the entire disconnection of their definitions. There is no reason, derivable from these definitions, why there should be any close association between the strain-locus of an experient occasion and any duration including that occasion among its members. It is an empirical fact that mankind invariably conceives the presented world as consisting of such a duration. This is the contemporary world as immediately perceived by the senses. But close association does not necessarily involve unqualified identification. It is permissible, in framing a cosmology to accord with scientific theory, to assume that the associated pair, strain-locus and presented duration, do not involve one and the same extensive region. From the point of view of conscious perp. 493ception, the divergence may be negligible, though important for scientific theory.

SECTION II

THE notions which have led to the phraseology characterizing the ‘projected’ sensa as ‘secondary qualities’ arise out of a fundamental difference between ‘strain-loci’ and their associated ‘presented durations.’ <A strain-locus is entirely determined by the experient in question. It extends beyond that experient indefinitely, although defined by geometrical elements entirely within the extensive region which is the standpoint of the experient. The ‘seat’ of the strain-locus, which is a set of points within this region, is sufficient to effect this definition of the complete strain-locus by the aid of the straight lines termed the ‘projectors.’ These straight lines are nexts whose geometrical relations are forms ingredient in a strain-feeling with these nexiis as data. Presentational immediacy arises from the integration of a strain-feeling and a ‘physical purpose,’ so that, by the category of transmutation, the sensum involved in the ‘physical purpose’ is projected onto some external focal region defined by projectors.

It is to be noted that this doctrine of presentational immediacy and of the strain-locus entirely depends upon a definition of straight lines in terms of mere extensiveness. If the definition depends upon the actual physical occasions beyond the experient, the experient should find the actual physical structures of his environment a block, or an assistance, to his ‘projection’ to focal regions beyond them. The projection of sensa in presentational immediacy depends entirely upon the state of the brain and upon systematic geometrical relations characterizing the brain. How the brain is excited, whether by visual stimuli through the eye, or by auditory stimuli through the ear, or by the excessive consumption of alcohol, or by hysterical emotion, is completely indifferent; granted the proper excitement of the brain, the experient will per-

p. 494

ceive some definite contemporary region illustrated by the projected sensa. The indifference of presentational immediacy to contemporary actualities in the environment cannot be exaggerated. It is only by reason of the fortunate dependence of the experient and of these contemporary actualities on a common past, that presentational immediacy is more than a barren aesthetic display. It does display something, namely, the real extensiveness of the contemporary world. It involves the contemporary actualities but only objectifies them as conditioned by extensive relations. It displays a system pervading the world, a world including and transcending the experient. It is a vivid display of systematic real potentiality, inclusive of the experient and reaching beyond it. In so far as straight lines can only be defined in terms of measurements, requiring particular actual occasions for their performance, the theory of geometry lacks the requisite disengagement from particular physical fact. The requisite geometrical forms can then only be introduced after examination of the particular actual occasions required for measurement. But the theory of ‘projection,’ explained above, requires that the definition of a complete straight line be logically prior to the particular actualities in the extensive environment. This requisite has been supplied by the preceding theory of straight lines (cf. previous chapter). The projectors do depend upon the one experient occasion. But even this dependence merely requires that component feelings of that occasion should participate in certain geometric elements, namely, a set of points, and the straight lines defined by them, among their data. Thus, according to this explanation, presentational immediacy is the mode in which vivid feelings of contemporary geometrical relations, with especial emphasis on certain ‘focal’ regions, enter into experience.

This doctrine is what common sense always assumes.
When we see a coloured shape, it may be a real man, or a
ghost, or an image behind a mirror, or an hallucination;

p. 495