Scholarly, Formal
Although Freud can be very frank and revealing throughout The Interpretation of Dreams, his writing style still sticks to the formal academic and professional standards of his day. Want a taste of what that means? Check out this passage from the preface to the first German-language edition of the book, where Freud attempts to explain himself as tactfully as he can:
The only dreams open to my choice were my own and those of my patients undergoing psycho-analytic treatment. But I was precluded from using the latter material by the fact that in its case the dream-processes were subject to an undesirable complication owing to the added presence of neurotic features. But if I was to report my own dreams, it inevitably followed that I should have to reveal to the public gaze more of the intimacies of my mental life than I liked, or than is normally necessary for any writer who is a man of science and not a poet. (source)
Although Freud acknowledges that some of the content of The Interpretation of Dreams may seem better suited to the realm of "poetry" than to the realm of "science," he nevertheless tries to maintain a formal, scholarly style in his writing—no matter how intimate or sexually explicit things get.