The Interpretation of Dreams by Sigmund Freud Chapter 2 Page 20

with the momentous in the psychical estimation of the individual. It is only the action of displacement if what is indifferent obtains recognition in the dream content instead of those impressions which are really the stimulus, or instead of the things of real interest. In answering the question as to what provokes the dream, as to the connection of the dream, in the daily troubles, we must say, in terms of the insight given us by replacing the manifest latent dream content: The dream does never trouble itself about things which are not deserving of our concern during the day, and trivialities which do not trouble us during the day have no power to pursue us whilst asleep.

What provoked the dream in the example which we have analyzed? The really unimportant event, that a friend invited me to a free ride in his cab.