A very similar kind of unification takes place between sequent images under the form of transformation.  When two images follow one another closely, and have anything in common, they readily assume the form of a transmutation.  There is a sort of overlapping of the mental images, and so an appearance of continuity produced in some respects analogous to that which arises in the wheel-of-life (thaumatrope) class of sense-illusions.  This would seem to account for the odd transformations of personality which not unfrequently occur in dreams, in which a person appears, by a kind of metempsychosis, to transfer his physical ego to another, and in which the dreamer’s own bodily phantom plays similar freaks.  And the same principle probably explains those dissolving-view effects which are so familiar an accompaniment of dream-scenery.[94]

But passing from this exceptional kind of unity in dreams, let us inquire how the heterogeneous elements of our dream-fancy become ordered and arranged when they preserve their separate existence.  If we look closely at the structure of our more finished dreams, we find that the appearance of harmony, connectedness, or order, may be given in one of two ways.  There may, first of all, be a subjective harmony, the various images being held together by an emotional thread.  Or there may, secondly, be an objective harmony, the parts of the dream, though answering to no particular experiences of waking life, bearing a certain resemblance to our habitual modes of experience.  Let us inquire into the way in which each kind of order is brought about.

Lyrical Element in Dreams.

The only unity that belongs to many of our dreams is a subjective emotional unity.  This is the basis of harmony in lyrical poetry, where the succession of images turns mainly on their emotional colouring.  Thus, the images that float before the mind of the Poet Laureate, in his In Memoriam, clearly have their link of connection in their common emotional tone, rather than in any logical continuity.  Dreaming has been likened to poetic composition, and certainly many of our dreams are built upon a groundwork of lyrical feeling.  They might be marked off, perhaps, as our lyrical dreams.

The way in which this emotional force acts in these cases has already been hinted at.  We have seen that the analogy of feeling is a common link between dream-images.  Now, if any shade of feeling becomes fixed and dominant in the mind, it will tend to control all the images of the time, allowing certain congruous ones to enter, and excluding others.[95] If, for example, a feeling of distress occupies the mind, distressing images will have the advantage in the struggle for existence which goes on in the world of mind as well as in that of matter.  We may say that attention, which is here wholly a passive process, is controlled by the emotion of the time, and bent in the direction of congruent or harmonious images.