§ 1. Ideal Prearrangement distinguished from Perceptual Preadjustment. — Perceptual activity is guided by the actual presence of perceived objects. It is true that perceptual activity constantly involves preadjustment of the body and senseorgans for coming impressions. But this preadjustment is directly prompted by present or past impressions, and it consists, not in a predetermination of the future, but merely in an appropriate waiting attitude. The only means by which the perceptual consciousness can control the course of its experience is through actual bodily movement. But no bodily movement can overleap a period of time. The most agile animal cannot take a spring into the future. But the ideational consciousness can cross a bridge before coming to it. It can begin by the ideal anticipation of the end, and it can move freely to and fro over the series of links intervening between end and startingpoint. Thus, if it meets a difficulty midway in the series, it need not provide for that difficulty at the point where it emerges. It may go backward to an earlier stage or even to the beginning, and there make a suitable rearrangement. It is plain that the process admits of all kinds of variations, and readjustments of part to part, which are impossible for perceptual consciousness.