An association will thus be formed between this person and the idea of death.

A night or two after, the image of this person somehow recurs to our dream-fancy, and we straightway dream that we are looking at his corpse, watching his funeral, and so on.

The links of the chain which holds together these dream-images were really forged, in part, in our waking hours, though the process was so rapid as to escape our attention.

It may be added, that in many cases where a juxtaposition of dream-images seems to have no basis in waking life, careful reflection will occasionally bring to light some actual conjunction of impressions so momentary as to have faded from our recollection.
We must remember, further, how great an apparent disorder will invade our imaginative dream-life when the binding force of resemblance has unchecked play.

In waking thought we have to connect things according to their essential resemblances, classifying objects and events for purposes of knowledge or action, according to their widest or their most important points of similarity.