THE PERCEPTION OF SPACE, (ill.) 347

warrant the conclusions drawn from them, and that the feeling in question is probably a wholly fictitious entity. 1 Meanwhile it suffices to point out that even those who set most store by it are compelled, by the readiness with which the translocation of the field of view becomes corrected and further errors avoided, to admit that the precise space- import of the supposed sensation of outgoing energy is as ambiguous and indeterminate as that of any other of the eye- feelings we have considered hitherto. I have now given what no one will call an understate- ment of the facts and arguments by which it is sought to banish the credit of directly revealing space from each and every kind of eye-sensation taken by itself. The reader will confess that they make a very plausible show, and most likely wonder whether my own theory of the matter can rally from their damaging evidence. But the case is far from being hopeless ; and the introduction of a discrimina- tion hitherto unmade will, if I mistake not, easily vindicate the view adopted in these pages, whilst at the same time it makes ungrudging allowance for all the ambiguity and illusion on which so much stress is laid by the advocates of the intelle'ctualiet theory. (e) The Choice of the Visual Reality. We have native and fixed optical space-sensations ; but ex- perience leads us to select certain ones from among them to be the exclusive bearers of reality: the rest become mere signs and suggesters of these. The factor of selection, on which we have already laid so much stress, here as elsewhere is the solving word of the enigma. If Helmholtz, Wundt and the rest, with an ambiguous retinal sensation before them, meaning now one size and distance, and now another, had not contented them- selves with merely saying : The size and distance are not this sensation, they are something beyond it which it merely calls up, and whose own birth-place is afar in ' synthesis ' (Wundt) or in * experience ' (Helmholtz) as the case may 1 Cp. " The Feeling of Effort" in the Anniversary Memoirs of the Boston Society of Natural History, Boston, 1880. The only fact I am acquainted with which still seems to make for a feeling of innervation is the illusion of movement described by Mach on pp. 65-6 of his Beitrdge zur Analyse der Empfindungen (1886). Not having yet experimentally verified Mach's ob- servation, I am unable to criticise his explanation of it. The consequence is that the theory of the Innervations gefiihl has the last word in the discus- sion. But its existence or non-existence is quite immaterial, as far as my own space-theory is concerned.