I've read the opinion that Freud's work, "The Interpretation of Dreams," may have been his most influential. In that book he emphasized how dreams are stimulated from what might appear to be relatively insignificant occurrences of the day. I'm often impressed by how these occurrences express themselves, symbolically and usually visually, in the actual or manifest content of a dream.
For example, yesterday I received a short e-mail from a local library indicating that their fall calender was full and wouldn't be able to hold a reading for the poetry book my sister and I will be publishing this coming October. The e-mail also indicated I might try to again schedule the reading at the beginning of 2014. In a relatively long dream that night, toward the end I found myself competing in a tennis match with one of my former tennis partners. I won the first point, but when I moved to the ad-court for the second I found it cluttered with all sorts of junk that prevented us from continuing to play. The junk included several bookshelves, which, to me, was a reference to the e-mail about our poetry book, a kind-of putting off of the poetry game.