"Now, when several complex impressions which are more or less different from one another -- let us say that out of ten impressions in each, six are the same in all, and four are different from all the rest -- are successively presented to the mind, it is easy to see what must be the nature of the result.The repetition of the six similar impressions will strengthen the six corresponding elements of the complex idea, which will therefore acquire greater vividness; while the four differing impressions of each will not only acquire no greater strength than they had at first, but, in accordance with the law of association, they will all tend to appear at once, and will thus neutralize one another.
"This mental operation may be rendered comprehensible by considering what takes place in the formation of compound photographs when the images of the faces of six sitters, for example, are each received on the same photographic plate, for a sixth of the time requisite to take one portrait.The final result is that all those points in which the six faces agree are brought out strongly, while all those in which they differ are left vague; and thus what may be termed a generic portrait of the six, in contradistinction to a specific portrait of any one, is produced.
"Thus our ideas of single complex impressions are incomplete in one way, and those of numerous, more or less similar, complex impressions are incomplete in another way; that is to say, they are generic , not specific.And hence it follows that our ideas of the impressions in question are not, in the strict sense of the word, copies of those impressions; while, at the same time, they may exist in the mind independently of language.
"The generic ideas which are formed from several similar, but not identical, complex experiences are what are called abstract or general ideas; and Berkeley endeavored to prove that all general ideas are nothing but particular ideas annexed to a certain term, which gives them a more extensive signification, and makes them recall, upon occasion, other individuals which are similar to them.Hume says that he regards this as 'one of the greatest and the most valuable discoveries that has been made of late years in the republic of letters,' and endeavors to confirm it in such a manner that it shall be 'put beyond all doubt and controversy.'
"I may venture to express a doubt whether he has succeeded in his object; but the subject is an abstruse one; and I must content myself with the remark, that though Berkeley's view appears to be largely applicable to such general ideas as are formed after language has been acquired, and to all the more abstract sort of conceptions, yet that general ideas of sensible objects may nevertheless be produced in the way indicated, and may exist independently of language.In dreams, one sees houses, trees, and other objects, which are perfectly recognizable as such, but which remind one of the actual objects as seen I out of the corner of the eye, or of the pictures thrown by a badly-focussed magic lantern.A man addresses us who is like a figure seen in twilight, or we travel through countries where every feature of the scenery is vague; the outlines of the hills are ill-marked, and the rivers have no defined banks.
They are, in short, generic ideas of many past impressions of men, hills, and rivers.An anatomist who occupies himself intently with the examination of several specimens of some new kind of animal, in course of time acquires so vivid a conception of its form and struc-ture that the idea may take visible shape and become a sort of waking dream.But the figure which thus presents itself is generic, not specific.It is no copy of any one specimen, but, more or less, a mean of the series; and there seems no reason to doubt that the minds of children before they learn to speak, and of deaf-mutes, are peopled with similarly generated generic ideas of sensible objects." Are Vague Images 'Abstract Ideas' ?
The only point which I am tempted to criticise in this account is Prof.Huxley's identification of these generic images with 'abstract or general ideas' in the sense of universal conceptions.
Taine gives the truer view.He writes:
"Some years ago I saw in England, in Kew Gardens, for the first time, araucarias, and I walked along the beds looking at these strange plants, with their rigid bark and compact, short, scaly leaves, of a sombre green, whose abrupt, rough, bristling form cut in upon the fine softly-lighted turf of the fresh grass-plat.If I now inquire what this, experience has left in me, I find, first, the sensible representation of an araucaria; in fact, I have been able to describe almost exactly the form and color of the plant.But there is a difference between this representation and the former sensations, of which it is the present echo.The internal semblance, from which I have just made my description, is vague, and my past sensations were precise.For, assuredly, each of the araucarias I
saw then excited in me a distinct visual sensation; there are no two absolutely similar plants in nature; I observed perhaps twenty or thirty araucarias;
