must get our knowledge into some sort of unity, otherwise it can neither be retained nor used. The Ptolemaic system of astronomy was far better than none; it served as a framework for a great body of facts, distorted though they were by the false theory. We are lovers of systems. Most of us prefer unity to verity. We want order and discipline among our ideas. Of absolute truth we can not speak; of order and consistency we may. Any new system may find numerous adherents, if only it be presented in the threefold form of unity, consistency, and repetition. It is easy to understand this love of systems. They save us from the inevitable mental bankruptcy which would result from the influx of a mass of uncoördinated impressions. Grant us a system, all complete in its several compartments, where we can pigeon-hole each newly acquired fact, and peace and harmony reign within. No matter if the system be so narrow that we can dispose therein only a limited number of impressions; if only we have confidence in it, all heterogeneous elements we may cast out as "error." We love harmony and hate antagonisms. It is mental economy, therefore, for us to read the organs of our sects and parties, to converse with those with whom we sympathize, to listen to that which we believe already. Great historical disturbances bring out systems. It is in this way that we get ourselves ready for troublous times. A system is a kind of mental fortress, a vantage-ground from which to scrutinize each new idea, and apperceive it as a friend to be received or an enemy to be, on a priori grounds, repelled. System-forming is thus the process of mental involution, which is the law of individual minds, as evolution is of the mind of the race.
Mental involution shows another phase in habit. Habits are well-knit associations. They make us machines, committed forever to a determined manner of acting and thinking. A habit is itself a mental bias. Stereotyped and inherited, it becomes instinct, where we see the full fruition of the involution movement and the dead level of automatism. From this point of view, instinct has been well called "lapsed intelligence," if by intelligence we mean power to adapt ourselves to new surroundings and to avail ourselves of new impressions. Habit is opposed to progress. In history, our reformers—Jesus, Savonarola, Luther—have been habit-breakers. Genius, too, is only the name of that disposition which rebels against the law of mental involution, breaks away from systems, and goes out in search of the objective truths of nature. Thus, side by side with the involution movement, we find the evolution movement. In the animal kingdom, it is represented by the persistent but mysterious tendency toward variation; in human history, by the comet-like appearance of the reformer; in art, by the lawless product of genius. All these are
