While the determination of individual skill in the performance of a given operation is not, strictly speaking, a test of intelligence or of mental capacity, it has been established that the most accurate and speedy method of discovering the precise degree of skill possessed by any artisan is closely analogous to the scientific method of mental measurement. It has been found, moreover, that there is quite a close relation between an individual workman’s skill at his trade and the degree of mental capacity disclosed by the Mentimeter or similar scientific tests; the more intelligent the worker, the greater his skill if he has any natural aptitude for his trade. Many persons view with skepticism the idea that a workman’s degree of skill at his trade can be determined by tests that require but a few minutes. A month, they argue, is little enough for an expert foreman to classify justly the men under him, after observing their skill with his own eyes. When it is proposed that those who apply the tests for any trade need not themselves be skilled in it and may, in fact, know nothing about it, it is no wonder that they doubt the practicality of a method so foreign to previous conceptions and practice. Psychologists have long realized that the same methods by which mental qualities, abilities, and capacities are determined, analyzed, and measured, could be applied to the measurement of manual dexterity or the combination of manual dexterity, judgment, perception, adaptability, and patience that, taken together, make the skilled workman. For, as the reader who has perused this book thus far will long since have recognized, there is included in the foregoing list of qualities a predominance of those which come quite definitely under the classification of mental abilities or capacities. As has been previously pointed out, it is impossible to separate mental and physical powers, and psychologists do not regard the mind as a separate entity, but merely as a convenient term for the definition of certain of the higher physical powers and their manifestations. And just as a certain type of nervous (physical) organism manifests itself in the development of abilities which we are accustomed to term “intellectual” or “mental,” so the abilities which we call “physical” or “manual” are merely other manifestations of a different type of nervous organism.