For a full examination of the relation between reality and scientific symbolism, consult Ward, _Naturalism and Agnosticism_, part 1. The more clearly it is realised that scientific hypotheses are essentially a system of mathematical symbolism, the more impossible it becomes to suppose that they deal directly with the concrete nature of things. Footnote 40: In _Principles of Human Knowledge_, §§ 70-75, Berkeley indeed seems on the very verge of denying that God Himself “perceives” the “ideas” which by His action He excites in us. But at § 139 we find that a “spirit” means “that which perceives ideas, and wills and reasons about them,” and in the third Dialogue it is expressly stated that sensible things are “perceived by God” [Works, Edit. in Bohn’s Libraries, vol. i. p. 368]. In fact, from the psychological standpoint of Berkeleian sensationalism, to deny God’s possession of “ideas” (_i.e._ sense-contents) would have been tantamount to denying His spirituality. Footnote 41: Unfortunately Berkeley, like so many philosophers, thought of “activity” as primarily an external relation between a “cause” and the material on which it “works.” This is probably why he failed to realise the “active” character of the perceptual process. Footnote 42: The reader will do well to compare with the whole of the foregoing section the treatment of perception as essentially teleological in Dr. Stout’s _Manual of Psychology_,^3 bk. iii. pt. 1, chap. 2. I need hardly observe that recognition of the fundamental significance of purpose and selection for mental life does not of itself entail the adoption of “voluntarist” views in Psychology. What is fundamental for real mental life may perfectly well admit of analysis into hypothetical simpler elements for the purpose of the psychologist. Thus the admission that all mental life is teleological and selective need not involve the adoption of such metaphysical theories of activity as are adversely criticised by Mr. Bradley in his _Appearance and Reality_, chap. 7, or the introduction of a peculiar “consciousness of activity” as an unanalysable datum into Psychology. The antithesis between the actualities of life and the data of Psychology maintained by Prof. Münsterberg in his _Psychology and Life_, and _Grundzüge der Psychologie_, if untenable in the extreme form in which he states it, is important as a corrective of the opposite tendency to treat as ultimate for psychological analysis whatever is of supreme importance for life. Footnote 43: Thing-_in-itself_, _i.e._ not affected by the—according to this doctrine—extraneous conditions imposed upon it by relation to an experiencing mind. Footnote 44: