Process and Reality — the Gifford Lectures, 1929

with distinctness by reason of some peculiar feat of original supplementation which retains its undimmed importance in subsequent transmission. Other members of the chain may sink into oblivion. For example, in touch there is a reference to the stone in contact with the hand, and a reference to the hand; but in normal, healthy, bodily operations the chain of occasions along the arm sinks into the background, almost into complete oblivion. Thus M, which has some analytic consciousness of its datum, is conscious of the feeling in its hand as the hand touches the stone. According to this account, perception in its primary form is consciousness of the causal efficacy of the external world by reason of which the percipient is a concrescence from a definitely constituted datum. The vector character of the datum is this causal efficacy.

Thus perception, in this primary sense, is perception of the settled world in the past as constituted by its feeling-tones, and as efficacious by reason of those feelingtones. Perception, in this sense of the term, will be called ‘perception in the mode of causal efficacity.’ Memory is an example of perception in this mode. For memory is perception relating to the data from some historic route of ultimate percipient subjects M,, M2, Ms, etc., leading up to M which is the memorizing percipient.

SECTION VII

It is evident that ‘perception in the mode of causal efficacy’ is not that sort of perception which has received chief attention in the philosophical tradition. Philosophers have disdained the information about the universe obtained through their visceral feelings, and have concentrated on visual feelings.

What we ordinarily term our visual perceptions are the result of the later stages in the concrescence of the percipient occasion. When we register in consciousness our visual perception of a grey stone, something more than bare sight is meant. The ‘stone’ has a reference

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to its past, when it could be used as missile if small enough, or as a seat if large enough. A ‘stone’ has certainly a history, and probably a future. It is one of the elements in the actual world which has got to be referred to as an actual reason and not as an abstract potentiality. But we all know that the mere sight involved, in the perception of the grey stone, is the sight of a grey shape contemporaneous with the percipient, and with certain spatial relations to the percipient, more or less vaguely defined. Thus the mere sight is confined to the illustration of the geometrical perspective relatedness, of a certain contemporary spatial region, to the percipient, the illustration being effected by the mediation of ‘grey.’ The sensum ‘grey’ rescues that region from its vague confusion with other regions.

Perception which merely, by means of a sensum, rescues from vagueness a contemporary spatial region, in respect to its spatial shape and its spatial perspective from the percipient, will be called ‘perception in the mode of presentational immediacy.’

Perception in this mode has already been considered in Part II, Chapter II. A more elaborate discussion of it can now be undertaken.* The definition, which has just been given, extends beyond the particular case of sight. The unravelling of the complex interplay between the two modes of perception—causal efficacy and presentational immediacy is one main problem of the theory of perception.© The ordinary philosophical discussion of perception is almost wholly concerned with this interplay, and ignores the two pure modes which are essential for its proper explanation. The interplay between the two modes will be termed ‘symbolic reference.’

“ Also of subsequent discussions in Parts III and IV.

5 Cf. my Barbour-Page lectures, Symbolism, Its Meaning and Importance, delivered at the University of Virginia, April, 1927, Macmillan. Another discussion of this question is there undertaken, with other illustrations. Cf. also Professor Norman Kemp Smith’s Prolegomena to an Idealist Theory of Knowledge, Macmillan, 1924,

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Such symbolic reference is so habitual in human experience that great care is required to distinguish the two modes. In order to find obvious examples of the pure mode of causal efficacy we must have recourse to the viscera and to memory; and to find examples of the pure mode of presentational immediacy we must have recourse to so-called ‘delusive’ perceptions. For example, the image of a grey stone as seen in a mirror illustrates the space behind the mirror; the visual delusions arising from some delirium, or some imaginative excitement, illustrate surrounding spatial regions; analogously for the double-vision due to maladjustment of the eyes; the sight at night, of the stars and nebulae and Milky Way, illustrates vague regions of the contemporary sky; the feelings in amputated limbs illustrate spaces beyond the actual body; a bodily pain, referred to some part not the cause of the disorder, illustrates the painful region though not the pain-giving region. All these are perfectly good examples of the pure mode of presentational immediacy.

The epithet ‘delusive,’ which fits many, if not all, of these examples of presentational immediacy, is evidence that the mediating eternal object is not to be ascribed to the donation of the perceived region. It must have acquired its ingression in this mode from one of the originative phases of the percipient occasion. To this extent, the philosophy of organism is in agreement with the seventeenth-century doctrine of primary and secondary qualities, the mediating eternal object being, in this mode of ingression, a secondary quality. But in the philosophy of organism the doctrine does not have the consequences which follow in the earlier philosophies.

The account of perception in the pure mode of presentational immediacy, which has just been given, agrees absolutely with Descartes’ doctrine of perception in general, so far as can be Judged from his arguments which presuppose perception, and putting aside a few detached

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