20 PKOF. W. JAMES :

And now let us revert to the query propounded a moment since : Can these differences of mere quality in feeling, vary- ing according to locality yet having each sensibly and in- trinsically and by itself nothing to do with position, con- stitute the ' susceptibilities ' we mentioned, the conditions of being perceived in position, of the localities to which they belong ? The numbers on a row of houses, the initial letters of a set of words, have no intrinsic kinship with points of space, and yet they are the conditions of our knowledge where any house is in the row, or any word in the dictionary. Can the modifications of feeling in question be tags or labels of this kind which in no wise originally reveal the position of the spot to which they are attached, but guide us to it by what Berkeley would call a "customary tie"? Many authors have unhesitatingly replied in the affirmative. Lotze, who in his Medizinische Psychologic, 1 first described the sensations in this way, designated them, thus conceived, as local-signs. This term has obtained wide currency in Ger- many, and in speaking of the ' Local-sign theory ' hereafter, I shall always mean the theory which denies that there can be in a sensation any element of actual locality, of inherent spatial order, any tone as it were which cries to us imme- diately and without further ado, ' I am here,' or ' I am there ' . If, as may well be the case, we by this time find ourselves tempted to accept the Local-sign theory in a general way, we have to clear up several farther matters. If a sign is to lead us to the thing it means, we must have some other source of knowledge of that thing. Either the thing has been given in a previous experience of which the sign also formed part they are associated; or it is what Keid calls a 'natural' preted by us, not as differences in the objective colour, but as distinctions in its locality. Lotze (Medizinische Psychologie, 333, 355), on the other hand, has pointed out the peculiar tendency which each particular point of the retina has to call forth that movement of the eye-ball which will carry the image of the exciting object from the point in question to the fovea. With each separate tendency to movement (as with each actual movement) we may suppose a peculiar modification of sensibility to be conjoined. This modification would constitute the peculiar local tinging of the image by each point. See also Sully 's Psychology, pp. 118-121. Prof. B. Erdman has quite lately (Vierteljahrsschrift f. wiss. Phil., x. 324-9) denied the existence of all evidence for such immanent gualia of feeling characterising each locality. Acute as his remarks are, they quite fail to convince me. On the skin the qualia are evident, I should say. Where, as on the retina, they are less so (Kries and Auerbach), this may well be a mere difficulty of discrimination not yet educated to the analysis. 1 1852, p. 331.