Freud, as a psychoanalyst, was interested in interpreting dreams to uncover repression and wishes or hopes. With the latter, he supposed that such dreams illustrate (usually in nonlinear, distorted or condensed form) some unfulfilled wish, something the patient wants - will want in the future. In this essay, Freud continues his interest in dreams but shifts from what patients dream to "dreams which have never been dreamed" - that is dreams thought and written by authors. Even if his analysis yields nothing helpful to psychoanalysis in general, Freud supposed that it will shed light on literary creations and maybe even conscious dream production (as opposed to the unconscious dream production we do when sleeping).
Even if the investigation should teach nothing of the nature of dreams, it may perhaps afford us, from this angle, a little insight into the nature of creative, literary production.
Freud's essay is a study on Wilhelm Jensen's Gradiva, which is about an archaeologist (Norbert) who develops an emotional attachment to a bas-relief (carved figure raised from the surface - like the figures on coins). He has no scientific need (as an archaeologist) for the relief but finds it very striking. Norbert has a dream that the woman figure (Gradiva) was lost at the destruction of Pompeii in the year 79 but was also, beyond his conscious awareness, his contemporary (alive during his time). Norbert is affected by his dream and goes to Pompeii.
He later meets a woman who resembles the woman figure on the relief and through the process of getting to know her, he realizes that it is his childhood friend (Zoe) who he's always had feelings for, but repressed them over time. It is interesting to note that he is an archaeologist, one devoted to studying the past, but he needed the real woman to help him realize this and also help him to realize why he had become attached to the figure on the relief: the figure reminded him of this childhood friend.
This is a useful text to use because it engages in two parallels: the past and present, the conscious and unconscious. Zoe also acts as a kind of therapist introducing notions of transference.
Norbert had to uncover his obsession with Gravida as if it were buried in Pompeii's ashes way back in the year 79. This is a most useful analogy for uncovering the repressed thoughts of his own memory to discover that his obsession with Gradiva was based on a memory of his own - also buried in the (his) past.