540 THE POPULAR SCIENCE MONTHLY. 



brevity I chiefly confine my remarks to visual representations, they are 

 intended to apply equally to all the senses. 



A generic image appears to be nothing more than a generic por- 

 trait stamped on the brain by the successive impressions made by its 

 component images. Professor Huxley, from whom I have borrowed 

 the apt phrase, has expressed himself to a similar effect in his recent 

 "Life of Hume," page 95. I am rejoiced to find that from a strictly 

 physiological side this explanation is considered to be the true one, by 

 so high an authority, and that he has, quite independently of myself, 

 adopted a view which I also entertained, and had hinted at in my first 

 description of composite portraiture, though there was not occasion 

 at that time to write more explicitly about it. 



When I am adjusting portraits to make a composite, and at the 

 moment when the adjustment is being effected, I always experience a 

 quick sense of satisfaction curiously analogous to that which is felt 

 on the first recognition of a doubtful likeness of any kind. I have 

 the same disagreeable feeling of the existence of a puzzle which I 

 can not make out, accompanied by the conviction that the puzzle is 

 on the point of being solved. In the next instant coalescence takes 

 place between what is seen and what was recollected. I am as sure 

 as it is possible to be on such grounds as these, that the analogy be- 

 tween catching the coincidence of two similar portraits when optically 

 superposed and that of the coincidence of a visible object with a past 

 impression or with a preexistent general idea is true and not meta- 

 phorical only. 



It is very instructive to note the first appearance of a generic 

 image, and to watch the way in which the mind carves images out of 

 the medley of its available material. It can not grasp an image of 

 any complexity unless the elements of which it consists form a con- 

 gruous composition, that is to say, one whose parts are connected by 

 such easy lines of association that the mind runs rapidly over the 

 whole of it, and takes it all in by what seems to be a single glance. 

 Generic images begin, at least according to my own experience, by 

 being exceedingly imperfect and vague because they are very com- 

 prehensive. Then limitations commence, each of which is the cause 

 of a more distinct picture being formed, and so the mind runs first 

 through genera, then through species, continually seeking more con- 

 gruity and clearer definition, but at each step with a loss of compre- 

 hensiveness. If allowed to do so, it descends to individuals. Let us, 

 as an example, call up a generic image of a clergyman preaching. I 

 first see a pulpit of somewhat undefined height? with a vague figure in 

 it. This figure becomes white, in a surplice ; a competing figure in a 

 black ground temporarily yielding place. Then I see various acces- 

 sories suitable to the surplice, such as Gothic architecture, ritualis- 

 tic decorations, and the like. After this the interiors of particular 

 churches begin to present themselves, but, as I wish to confine my 



