There is an absence of flexibility in the mental imagery of most persons.  They find that the first image they have acquired of any scene is apt to hold its place tenaciously in spite of subsequent need of correction.  They find a difficulty in shifting their mental view of an object, and examining it at pleasure in different positions.  If they see an object equally often in many positions the memories combine and confuse one another, forming a “composite” blur, which they cannot dissect into its components.  They are less able to visualise the features of intimate friends than those of persons of whom they have caught only a single glance.  Many such persons have expressed to me their grief at finding themselves powerless to recall the looks of dear relations whom they had lost, while they had no difficulty in recollecting faces that were uninteresting to them.

Others have a complete mastery over their mental images.  They can call up the figure of a friend and make it sit on a chair or stand up at will; they can make it turn round and attitudinise in any way, as by mounting it on a bicycle or compelling it to perform gymnastic feats on a trapeze.  They are able to build up elaborate geometric structures bit by bit in their mind’s eye, and add, subtract, or alter at will and at leisure.  This free action of a vivid visualising faculty is of much importance in connection with the higher processes of generalised thought, though it is commonly put to no such purpose, as may be easily explained by an example.  Suppose a person suddenly to accost another with the following words:—­ “I want to tell you about a boat.”  What is the idea that the word “boat” would be likely to call up?  I tried the experiment with this result.  One person, a young lady, said that she immediately saw the image of a rather large boat pushing off from the shore, and that it was full of ladies and gentlemen, the ladies being dressed in white and blue.  It is obvious that a tendency to give so specific an interpretation to a general word is absolutely opposed to philosophic thought.  Another person, who was accustomed to philosophise, said that the word “boat” had aroused no definite image, because he had purposely held his mind in suspense.  He had exerted himself not to lapse into any one of the special ideas that he felt the word boat was ready to call up, such as a skiff, wherry, barge, launch, punt, or dingy.  Much more did he refuse to think of any one of these with any particular freight or from any particular point of view.  A habit of suppressing mental imagery must therefore characterise men who deal much with abstract ideas; and as the power of dealing easily and firmly with these ideas is the surest criterion of a high order of intellect, we should expect that the visualising faculty would be starved by disuse among philosophers, and this is precisely what I found on inquiry to be the case.