Just as there are such dispositions to united action among various parts of one organ of sense, so there may be among different organs, which are either connected originally in the infant organism, or have communications opened up by frequent coexcitation of the two.  Such links there certainly are between the organs of taste and smell, and between the ear and the muscular system in general, and more particularly the vocal organ.[96] A new odour often sets us asking how the object would taste, and a series of sounds commonly disposes us to movement of some kind or another.  How far there may be finer threads of connection between other organs, such as the eye and the ear, which do not betray themselves amid the stronger forces of waking mental life, one cannot say.  Whatever their number, it is plain that they will exert their influence within the comparatively narrow limits of dream-life, serving to impress a certain character on the images which happen to be called up by special circumstances, and giving to the combination a slight measure of congruity.  Thus, if I were dreaming that I heard some lively music, and at the same time an image of a friend was anyhow excited, my dream-fancy might not improbably represent this person as performing a sequence of rhythmic movements, such as those of riding, dancing, etc.

A narrower field for these general associative dispositions may be found in the tendency, on the reception of an impression of a given character, to look for a certain kind of second impression; though the exact nature of this is unknown.  Thus, for example, the form and colour of a new flower suggest a scent, and the perception of a human form is accompanied by a vague representation of vocal utterances.  These general tendencies of association appear to me to be most potent influences in our dream-life.  The many strange human forms which float before our dream-fancy are apt to talk, move, and behave like men and women in general, however little they resemble their actual prototypes, and however little individual consistency of character is preserved by each of them.  Special conditions determine what they shall say or do; the general associative disposition accounts for their saying or doing something.

We thus seem to find in the purely passive processes of association some ground for that degree of natural coherence and rational order which our more mature dreams commonly possess.  These processes go far to explain, too, that odd mixture of rationality with improbability, of natural order and incongruity, which characterizes our dream-combinations.

Rational Construction in Dreams.