The images which go with words grow in fulness as one’s experience enlarges. Take the word fire. The first idea was formed from fire in the stove and in the smithy. A fuller idea resulted from the sight of a distant mountain on fire. Then a distant conflagration resulting in the loss of a block of town property gave the word still fuller content. Finally, the destruction of the State Capitol, in which part of the manuscript of a book, other valuable papers and records were destroyed, and in which one or two friends almost lost their lives, gave a meaning to the word fire which it never had before. Without doubt it hampers the mind and impedes the logical processes of thought if the word invariably calls up the idea of these fires with the accompanying emotions.
[Sidenote: Books on mathematics and other sciences.]
We saw the value of the labor-saving devices introduced by the symbols and formulas of mathematics and other sciences. Analysts carry forward long trains of thought by means of symbols whose meaning can be, but is not always, called up with the successive links of the chain of reasoning. In adding a column of figures, in solving an algebraic equation, in reading a work on higher mathematics or logic, in thinking the formulas of chemistry, physics, astronomy, etc., and in dealing with objects, forces, and relations which have been accurately and definitely quantified, the thinking may be carried forward by the use of symbols which can be interpreted and applied whenever the occasion requires, but whose meaning is not always present to the mind. In reading of things which have not been quantified, the stream of thought often flows on without images, or mental pictures, or copies of sensations. Nevertheless, the examination of any school reader or book of selections from the best literature will show how our best writers and orators appeal to the imagination, and to what a large field the method of thinking in images or mental pictures is applicable for the purpose of securing due appreciation of good literature and proper expression in oral reading.
The simplest thinking is the comparison of objects when these are present to the senses. It prevails largely in the handicrafts and in the ordinary duties of life. More difficult is the comparison of images or mental pictures of things when these are not present to the senses, but must be recalled by the memory. This thinking is essential to the appreciation of poetry, to the vivid presentation of thought, and should not be neglected by those who wish to move the multitudes with tongue or pen. “Imaging,” says Dryden, “is in itself the very height and life of poetry, which, by a kind of enthusiasm or extraordinary emotion of the soul, makes it seem to us that we behold those things which the poet paints.” Higher, from the scientist’s point of view, is the thinking in substitute symbols which stand for ideas definitely fixed or quantified. Higher still is the comparison of abstract and general ideas through expressive symbols, including their application to the problems of life; for this is the kind of thinking that characterizes the scientist and the philosopher, the engineer and the surgeon, the editor and the orator, and, in fact, all whose vocation has risen to the rank of a profession. But highest of all is the thinking which creates and invents, begetting progress in science and art, in literature and history, in government and civilization.