The profession of teaching owes Mr. Galton a special debt of gratitude for the light which his investigations throw upon the process of thinking. These investigations were published in a volume entitled “Inquiries into Human Faculty.” When he began to inquire among his friends as to their power to call up mental pictures of the breakfast-table, those engaged in scientific pursuits were inclined to consider him fanciful and fantastic in supposing that the words _mental imagery_ really expressed what he thought everybody supposed them to mean. He says they had no more notion of its true nature than a color-blind man who has not discerned his defect has of the nature of color. When he spoke to persons in general society, he got very different replies. Among other curious things which he discovered, he found that the power of thinking in sense-images, or mental pictures, may be partly inherited, partly developed by practice, and that it may be impaired by disuse or by the habit of hard thinking peculiar to men engaged in scientific pursuits. Scientific men, as a class, have feeble powers of visual representation. He reached the conclusion that “an over-ready perception of sharp mental pictures is antagonistic to the acquirement of highly generalized and abstract thought, especially when the steps of reasoning are carried on by words as symbols, and that if the faculty of seeing the pictures was ever possessed by men who think hard, it is very apt to be lost by disuse.”
He further claims that the visualizing faculty can be developed by education. This is very significant. It shows how unwise methods may harm our children in two directions. The wrong method may keep the mind at work in the concrete when the science under consideration demands more advanced and very different methods of thought. In the other direction the mind may be tied to words, descriptions, book methods, and symbolic representations, whereas the thinking which one’s future duties demand points in the direction of drawing, mechanics, and handicrafts, in which success turns upon the power of thinking in visual images and mental pictures. One cannot forbear quoting his language in so far as it bears upon the thinking developed by schools for manual training in distinction from the thinking developed by the university which aims to fit its students for the professions and for scientific thought and experimental research.