Page:Principles of Psychology (1890) v1.djvu/290

270 PSYCHOLOGY. measure to be let into his neighbor's mind and to find how different the scenery there was from that in his own. Thought is in fact a kind of Algebra, as Berkeley long ago said, " in which, though a particular quantity be marked by each letter, yet to proceed right, it is not requisite that in every step each letter suggest to your thoughts that par- ticular quantity it was appointed to stand for." Mr. Lewes has developed this algebra-analogy so well that I must quote his words : " The leading -characteristic of algebra is that of operation on rela- tions. This also is the leading characteristic of Thought. Algebra can- not exist without values, nor Thought without Feelings. The operations are so many blank forms till the values are assigned. Words are va- cant sounds, ideas are blank forms, unless they symbolize images and sensations which are their values. Nevertheless it is rigorously true, and of the greatest importance, that analysts carry on very extensive operations with blank forms, never pausing to supply the symbols with values until the calculation is completed; and ordinary men, no less than philosophers, carry on long trains of thought without pausing to translate their ideas (words) into images. . . . Suppose some one from a distance shouts ' a lion ! ' At once the man starts in alarm. . . . To the man the w^ord is not only an . . . expression of all that he has seen and heard of lions, capable of recalling various experiences, but is also capable of taking its place in a connected series of thoughts without recalling any of those experiences, without reviving an image, however faint, of the lion — simply as a sign of a certain relation Included in the complex so named. Like an algebraic symbol it may be operated on without conveying other significance than an abstract relation : it is a sign of Danger, related to fear with all its motor sequences. Its logical position suffices. . . . Ideas are substitutions which require a secondary process when what is symbolized by them is translated into the images and experiences it replaces; and this secondary process is frequently not performed at all, generally only performed to a very small extent. Let anyone closely examine what has passed in his mind when he has con- structed a chain of reasoning, and he will be surprised at the fewness and faintness of the images which have accompanied the ideas. Sup- pose you inform me that ' the blood rushed violently from the man's heart, quickening his pulse at the sight of his enemy. ' Of the many la- tent images in this phrase, how many were salient in your mind and in mine ? Probably two — the man and his enemy — and these images were faint. Images of blood, heart, violent rushing, pulse, quickening, and sight, were either not revived at all, or were passing shadows. Had any such images arisen, they would have hampered thought, retarding the logical process of judgment by irrelevant connections. The symbols had substituted relations for these values. . . . There are no images of