T he nature of imagination is somewhat difficult to under­ stand, chiefly because of the ambiguity of the word as commonly used. This ambiguity attaches mainly to the verb imagine, which is used in two senses which are really distinct; in one case it corresponds to the noun imagina­ tion, in the other to the noun image, and in psychology the two words have a very different meaning. We say we have a mental image when, without there being any external object to initiate the sensation, we have a mental experience such as might be given through any sense organ. Thus, as we dress in our bedroom, we can have an image of our breakfast table and see the food, the flowers and other appurtenances with more or less clearness; we can hear over again, i.e., have an auditory image of the “ Gilbert and Sullivan ” we heard last week, or we can see and feel, as images, the movements necessary for cutting a figure 8 in skating. We can also have images of taste and smell, though many people have these images less readily than visual or auditory ones.