reserve, as we have seen, plays a double part in the economy: it is a stock in abeyance, and it is the base of every present act. Without a reserve of mental energy, the mind can no more continue the healthful exercise of its functions than a flabby muscle without tonicity can respond to the stimulus of strong volition and lift a heavy weight or strike a heavy blow.
The cause, or condition, which most commonly exposes the reserve of mental energy to loss and injury is worry. The tone and strength of mind are seriously impaired by its wearing influence, and, if it continue long enough, they will be destroyed. It sets the organism of thought and feeling vibrating with emotions which are not consonant with the natural liberation of energy in work. The whole machinery is thrown out of gear, and exercise, which would otherwise be pleasurable and innocuous, becomes painful and even destructive. It is easy to see how this must be. The longest note in music, the most steady and persistent ray of light—to use an old-fashioned expression—the tonic muscular contraction, are all, we know, produced by a rapid succession of minute motive impulses or acts, like the explosion and discharge of electricity from alternately connected and separated points in a circuit; in fact, a series of vibrations. Mental energy doubtless takes the same form of development. If a disturbing element is introduced by the obtrusion of some independent source of anxiety, or if, out of the business in hand, the mind makes a discord, confusion ensues, and for the time being harmonious action ceases. Working under these conditions in obedience to the will, the mental organism sustains injury which must be great, and may be lasting. The function of the warning sense is suspended; the reserve is no longer a stock in abeyance, and it ceases to give stability to the mind; the rhythm of the mental forces is interrupted; a crash is always impending, and too often sudden collapse occurs. The point to be made clear is this: overwork is barely possible, and seldom, if ever, happens, while the mind is acting in the way prescribed by its constitution, and in the normal modes of mental exercise. The moment, however, the natural rhythm of work is broken and discord ensues, the mind is like an engine with the safety-valve locked, the steam-gauge falsified, the governing apparatus out of gear; a breakdown may occur at any instant. The state pictured is one of worry, and the besetting peril is not depicted in too lurid colors. The victim of worry is ever on the verge of a catastrophe: if he escape, the marvel is not at his strength of intellect so much as his good fortune. Worry is disorder, however induced, and disorderly work is abhorred by the laws of nature, which leave it wholly without remedy. The energy employed in industry carried on under this condition is lavished in producing a small result, and speedily exhausted. The reserve comes into play very early in the task, and the faculty of recuperation is speedily arrested. Sometimes loss of appetite announces the cessation of nutrition; otherwise