“Depend upon it, no one need be too much cast down by the discovery of his deficiency in any elementary faculty of the mind. . . . The total mental efficiency of a man is the resultant of all his faculties. He is too complex a being for any one of them to have the casting vote. If any one of them do have the casting vote, it is more likely to be the strength of his desire and passion, the strength of the interest he takes in what is proposed. Concentration, memory, reasoning power, inventiveness, excellence of the senses—all are subsidiary to this. No matter how scatter-brained the type of a man’s successive fields of consciousness may be, if he really _care_ for a subject, he will return to it incessantly from his incessant wanderings, and first and last do more with it, and get more results from it, than another person whose attention may be more continuous during a given interval, but whose passion for the subject is of a more languid and less permanent sort.”[25] XI BOOKS ON THINKING The reader who desires to study further on the subject of thinking will find a wide field before him—but he will have to search in cosmopolitan quarters. While much has been written on thinking, it has been in an incidental manner, and has found its way into books written mainly to illuminate other subjects. Among the few books or essays devoted exclusively or mainly to thinking may be mentioned:—John Locke, _The Conduct of the Understanding_; Isaac Watts, _The Improvement of the Mind_; Arnold Bennett, _Mental Efficiency_; T. Sharper Knowlson, _The Art of Thinking_; Arthur Schopenhauer, _On Thinking for Oneself_, in his _Essays_. The last is especially recommended. It is only about a dozen pages long, and is the most stimulating essay written on the subject. This, together with John Locke’s _Conduct_ (which, by the way, is also fairly short) may be considered the two “classics” in the meager literature on thinking. There is an extensive literature on the psychology of reasoning, on the “positive” science of thinking. The best single work on this subject is John Dewey’s _How We Think_. William James’ chapter on _Reasoning_ in his _Principles of Psychology_ might also be consulted with profit. S. S. Colvin’s, _The Learning Process_ contains some interesting chapters bearing on thought.