[Footnote 1:  Let me not be told that this contradicts a former article of mine, ‘Does consciousness exist?’ in the Journal of Philosophy for September 1, 1904 (see especially page 489), in which it was said that while ‘thoughts’ and ‘things’ have the same natures, the natures work ‘energetically’ on each other in the things (fire burns, water wets, etc.), but not in the thoughts.  Mental activity-trains are composed of thoughts, yet their members do work on each other:  they check, sustain, and introduce.  They do so when the activity is merely associational as well as when effort is there.  But, and this is my reply, they do so by other parts of their nature than those that energize physically.  One thought in every developed activity-series is a desire or thought of purpose, and all the other thoughts acquire a feeling tone from their relation of harmony or oppugnancy to this.  The interplay of these secondary tones (among which ‘interest,’ ‘difficulty,’ and ‘effort’ figure) runs the drama in the mental series.  In what we term the physical drama these qualities play absolutely no part.  The subject needs careful working out; but I can see no inconsistency.]

surface of a world whose real causality is an unimaginable ontological principle hidden in the cubic deeps, is, for the more empirical way of thinking, only animism in another shape.  You explain your given fact by your ‘principle,’ but the principle itself, when you look clearly at it, turns out to be nothing but a previous little spiritual copy of the fact.  Away from that one and only kind of fact your mind, considering causality, can never get.[1]

[Footnote 1:  I have found myself more than once accused in print of being the assertor of a metaphysical principle of activity.  Since literary misunderstandings retard the settlement of problems, I should like to say that such an interpretation of the pages I have published on effort and on will is absolutely foreign to what I meant to express.  I owe all my doctrines on this subject to Renouvier; and Renouvier, as I understand him, is (or at any rate then was) an out and out phenomenist, a denier of ‘forces’ in the most strenuous sense.  Single clauses in my writing, or sentences read out of their connexion, may possibly have been compatible with a transphenomenal principle of energy; but I defy any one to show a single sentence which, taken with its context, should be naturally held to advocate that view.  The misinterpretation probably arose at first from my having defended (after Renouvier) the indeterminism of our efforts.  ‘Free will’ was supposed by my critics to involve a supernatural agent.  As a matter of plain history, the only ‘free will’ I have ever thought of defending is the character of novelty in fresh activity-situations.  If an activity-process is the form of a whole ‘field of consciousness,’ and if each field of consciousness is not only in its totality unique (as is now commonly