As I have attempted to set forth in former efforts,[315] attention is probably in its earliest manifestations rather a means for the furtherance of the struggle for life than a so-called faculty of the mind. The instinct of lying in wait (by which we must understand not merely holding one’s self in readiness to seize prey, but also a preparedness for flight) is, as I conceive, the elementary form of attention. Some sense-perception called forth by the prey or the enemy, as the case may be, warns the animal to brace his organism for the utmost swiftness and accuracy of aim in view of what is coming; secondly, to hold his muscles tense and ready for lightning-quick reaction to the approaching stimulus; and, thirdly, to keep such restraint on his whole body as to repress all sounds and movements which might betray him. Among the higher animals, and especially man, “theoretic” attention has developed from this motor attention, which reacts to the anticipated stimulus with special external movements. In the former the reaction is an internal, brain process, not involving the second of the steps given above; it is sufficient to seize and master the object—to lie in wait apperceptively, as it were. The characteristic holding of the powers in check seems to argue the derivation of this sort of attention from the motor, thus grounding both on instinct. Expectancy is not then a variation, but rather a fundamental form of attention, and concentration on an object present before it results from a succession of constantly renewed expectations.