[Footnote 1: Dewey: loc. cit., p. 32.]
Curiosity passes thus from casual rudimentary inquiry into genuinely scientific investigation. At first it is merely physical manipulation, then merely disconnected questionings; it becomes genuinely intellectual when it passes from "inquisitiveness" to inquiry. To be inquisitive means merely to want to know facts rather than to solve problems. To be scientifically inquiring is to seek on one's own account the significant relations between things. But these earlier and more casual forms of curiosity are not to be despised. If developed and controlled they lead to genuinely disinterested study of Nature and of men, to the spirit and the methods of science. That free play of imagination which was spoken of above as the chief source of original thinking and discovery is stimulated by an active hunting-out of new suggestions. Curiosity might also be defined as aggressive imagination, which, frequent enough in children, remains among adults to a pronounced degree only in geniuses of art and science. We may not agree with Bertrand Russell that "everything is done in education to kill it," but the dogmatism and fixity of mind which so soon settle down on maturity, the inability to be sensitive to new experiences, these are discouragingly familiar phenomena clearly inimical to science and to progress.
An active imagination that finds new materials to play over is the basis of both science and art. A skillful manipulation of its materials in words or sounds, colors, or lines makes its result art. Their controlled examination and systematization makes them science.
Quiescence—Fatigue. That all life, animal and human, is characterized by activity of a more or less persistent and positive kind has already been noted. But in human beings, as well as in animals, activity displays a "fatigue curve." The repeated stimulation of certain muscles produces fatigue toxins which impair the efficiency of response and make further stimulation painful. Of the causes of this lessened functional efficiency we may quote from Miss Goldmark's painstaking study:
During activity, as will be shown later, the products of chemical change increase. A tired person is literally and actually a poisoned person—poisoned by his own waste products. But so marvellously is the body constructed that, like a running stream, it purifies itself, and during repose these toxic impurities are normally burned up by the oxygen brought by the blood, excreted by the kidneys, destroyed in the liver, or eliminated from the body through the lungs. So rest repaires fatigue.[1]
[Footnote 1: Goldmark, J.: Fatigue and Efficiency, p. 13.]
In physical activity, therefore, periods of lessened activity or change of activity, or nearly complete inactivity as in sleep, are not only desirable but necessary, if efficiency is to be maintained. The demand for rest is an imperative physiological demand. The amount of recuperation demanded by the organism varies in different individuals, but that there are certain limits of human productivity has been made increasingly clear by a careful study of the effects of fatigue upon output in industrial occupations. Repeatedly, the shortening of working hours, especially when they have previously numbered more than eight, has been found to be correlated with an increase in efficiency. Likewise, the provision of rest periods as in telephone-operating and the needle trades, has in nearly every case increased the amount and quality of the work performed. The human machine in order to be most effective cannot be pressed too hard. A striking illustration was offered in England at the beginning of the war. Under pressure of war necessity, the munition factories relaxed all restrictions on working hours and operated on a seven-day week. The folly of this procedure was tersely summarized by the British Commission investigating industrial fatigue, which reported: "It is almost a commonplace that seven days' labor produces six days' output."
In the study of industrial conditions, the effects of prolonged and repeated fatigue upon output have not been the only features taken into consideration. Not only are there immediately observable effects in the decreased output of the worker, but fatigue means, among other things, general loss of control. This has the effect of producing on the part of overworked factory hands dissipation and overstimulation in free time, with a consequent permanent impairment of efficiency.[1] Both for the laborer himself and for the efficiency of the industrial system, it has been increasingly recognized that limitation of working hours is imperatively demanded. Rest is as fundamental a need as food, and its deprivation almost as serious in its effects.
[Footnote 1: For a striking array of testimony on this point see Goldmark: loc. cit., pp. 220-35.]
Nervous and mental fatigue. The conditions of nervous and mental fatigue have been less adequately studied than the types of purely physiological fatigue just discussed. It is difficult in experiments to discount the effects of muscular fatigue, and to discover how far there is really impairment of nervous tissue and functions. Experimental studies do show that "nervous fatigue is an undoubted fact"[2] and that "we cannot deny fatigue to the psychic centers"[3] which, like any other part of the organism are subject to deterioration by fatigue toxins. Most students report, however, a higher degree of resistance to fatigue in the nerve fibers than in the muscles, and a like high resistance to fatigue in the brain centers.[4]