When did I say or imply that he was _aware_ of doing any of it? It is not only possible, but extremely common, to perform processes without being aware of performing them. The man was not _aware,_ for instance, of making eye adjustments and eye movements, unless indeed his sight was out of order. Yet his eye movements could have been cinematographed, and his eye adjustments have been described minutely in a dozen treatises. He was no more aware of _doing_ any measuring or comparing than we are aware of _doing_ our digestion or circulation, except when we do them badly. But just as we are aware of our digestive and circulatory processes in the sense of being aware of the animal spirits resulting from their adequate performance, so he was aware of his measuring and comparing, inasmuch as he was aware that the line A--B was longer than the line C--D, or that the point E was half an inch to the left of the point F. For so long as we are neither examining into ourselves, nor called upon to make a choice between two possible proceedings, nor forced to do or suffer something difficult or distressing, in fact so long as we are attending to whatever absorbs our attention and not to our processes of attending, those processes are replaced in our awareness by the very facts--for instance the proportions and relations of lines--resulting from their activity. That these results should not resemble their cause, that mental elements (as they are called) should appear and disappear, and also combine into unaccountable compounds (Browning's "not a third sound, but a star") according as we attend to them, is indeed the besetting difficulty of a science carried on by the very processes which it studies. But it is so because it is one of Psychology's basic facts. And, so far as we are at present concerned, this difference between mental processes and their results is the fact upon which psychological aesthetics are based. And it is not in order to convert the Man on the Hill to belief in his own acts of shape-perception, nor even to explain why he was not aware of them, that I am insisting upon this point. The principle I have been expounding, let us call it that of the _merging of the perceptive activities of the subject in the qualities of the object of perception,_ explains another and quite as important mental process which was going on in that unsuspecting man.