These ideas are of eminent importance for all higher mental development. Mind, in them, departs from that which nature presents, but only in order to take possession of it more securely by systematization and by overcoming the narrow limits of the capacity of consciousness.
By separating the common qualities of things from those which vary we classify the things into kinds and species, we think of them as being in various ways related. Instead of having an incomprehensible mass of things standing side by side, we have a system of coördinated and subordinated things, of groups formed according to closer or remoter relationship; and thus it becomes a comparatively easy matter to survey the multitude of things of which nature consists. Not only order, but law too is thus brought into the phenomena of nature. If we collect sticks of wood and set fire to the pile, we notice that some of them burn lustily, others smolder and smoke, still others do not burn at all. Why so? Repetition of similar experiences is necessary before we can give an answer; but mere repetition of the same event does not enable us to give the answer. The event must be broken up and general ideas must be formed out of the elements of the event. Then only can we answer the question. Some of the sticks burn because they are dry. Others do not burn so well or do not burn at all because they are wet. Neither shape nor color nor origin nor many other qualities of the sticks have any causal connection with the difference of burning and not burning. Both order and law in nature are recognized by abstraction.
Equally important is the overcoming of the narrowness of consciousness by abstraction and generalization. When I am thinking of trees, the contents of my mind are very few. There may be a word image, a visual image of something tall and branching; hardly more. All the special features of trees of all kinds are absent from consciousness. So I can easily think of additional things, for instance of the age which trees may reach, or the elevation at which trees cease to grow. But the moment I begin by accident to think of a thing which does not harmonize with those features of the tree which thus far have been absent from consciousness, immediately those features become conscious and inhibit the contradictory thoughts. They have been unconscious and yet we cannot say that they have been sheer nothing. The consciousness of the general idea has in some way prepared the path for the special features from which it has been abstracted. They have been carried close to the door of consciousness, so to speak, and the slightest impulse coming from an associated idea will cause them to enter. This is our meaning when we say that within the general idea of which we are conscious all those special features are included. They are included by representation, the general idea being the deputy taking care of their interests. Thus our mind is freed from the necessity of carrying at any moment a heavy load of actual states of consciousness and is nevertheless able to act as reasonably as if those mental states were present. In using representative ideas, our mind has actually at its service the enormous number of all those individual ideas which are represented by them.
QUESTIONS
134. Enumerate in what different respects ideation is (more or less) similar to perception.
135. Why are reproduced experiences fragmentary?
136. How does a general idea originate?
137. What is the difference between abstractions and general ideas?
138. Can an idea be both an abstraction and a general idea?
139. Illustrate the formation of a natural law by means of abstraction and generalization.