CHAPTER III

HOW AN IDEA ENTERS THE MIND

When an impression is made on a sense organ, the sensation derived from it is telegraphed up the connecting nerve fibre to the brain, and there translated, by a process of which we know nothing, from a sensation to a thought.

We believe that the mind learns by experience to associate certain kinds of sensation with certain objects or conditions in the environment, and when it feels these particular sensations, deduces that certain objects are present, and forms mental images, or thought models, intended to represent these objects.

The truth of our percepts is determined by the closeness with which our thought model corresponds to its original. An exact copy is a true concept, an imperfect copy an inaccurate concept.

We “recognise” an object by a process of classification, noting its likeness or unlikeness to other objects already known. When an unfamiliar object attracts our attention, we put it through a process of comparison until we find to which compartment in our concept-pictures it should be assigned, and if we cannot find a perfect match, we put it in the most suitable compartment we can discover, and then partition off a little subclass for it, thus admitting its identity in essentials, but its difference in details from the other occupants of that compartment.

For example, supposing we were to land on an island and an object on the shore attracted our attention, we should try to see what class of things of which we already had experience it most closely resembled. We should observe its movements, and assign it to the class of living creatures; see its four limbs and hair, and conclude it was an animal. Note its upright attitude, clothes, and weapons, and recognise these as characteristic of humanity; but perceiving that its skin differed in colour from that of any human being we had ever seen before, we should partition off a fresh subdivision in the department of our mind in which our ideas connected with humanity were stored, place it there, and probably give it a distinguishing name by means of which we could indicate it to other human beings.

Supposing, however, we presently come across another object of the same nature, we should not have to make a fresh subdivision for it, but would classify it with the previously examined specimen, and thus we should feel this time that we “knew what it was.” In fact, the process of “knowing” is a process of classification, and we feel that we “know” a thing when we have assigned it to a satisfactory pigeon-hole among our concepts.