§ 164
Every one of these twenty-odd different qualities of sense impression may enter consciousness from time to time as a representation or reverberation of an original sensation. The commonest of these is sight. The appearance of some facial expression, for example, of an attractive woman, will, spontaneously recur to a young man for a long time. Motivated by pleasurable emotions experienced at the first sight, these visual memory images will recur again and again, each time accompanied by, if not caused by, the continuance or reëmergence of the pleasurable emotions.
But visual images are not the only ones that spontaneously recur. If the individual belongs to the auditory type, there will be numerous auditory “images.” He will hear in his mind’s ear the joyous timbre of a woman’s voice, also perhaps motivated by the same recurrent pleasurable emotion he experienced when listening to it the first time.
Visual and auditory “images” or representations may be supplemented by those of any of the other twenty-odd qualities of sense impression. The memory of a dance recalls a number of these, tactual, olfactory, kinesthetic, mostly, however, in the average person, not clearly conscious.
People have to be taught to see what is before their eyes. They also have to be taught to recognize timbres of musical instruments, intervals between tones, composition of various chords, etc.
Conscious attention must be used to enable some people to recognize the difference between various flavours, perfumes, odours, bouquets of wine, etc.
This sharpening of sense discrimination is accomplished by means of the conscious attention to the various images.
The sharpening of sense discrimination with the assistance of the mental standard supplied by the various representations of former sense impressions involves a change in the sense organ itself if we include in the organ, as we must, its nerve connections with the brain and with other organs.