It is remarkable that these two senses, over and above that receptivity for impressions as is required to obtain concepts of external objects by means of these impressions, also admit of a peculiar associated sensation of which we cannot easily determine whether it is based on sensibility or reﬂection; and that this affectability may at times be lacking, although the sense, in other respects, and in what concerns its employment for the cognition of objects, is by no means deficient but particularly keen.