This paper traces the influence of Freud's adolescent language of flowers, a symbolic, metaphoric language of love, lust, and longing, from his youthful letters to Eduard Silberstein to later conceptualizations of his theory of sexuality, especially his 1905 theory of the transformations of puberty. In addition, information discovered by Boelich, editor of the Silberstein letters, sheds new light on the impetus for Freud's vigorous suppression of his adolescent poetic imagination and his adolescent crush on Gisela Fluss. The paper demonstrates that Freud's adolescent poetic imagination was transformed into a scientific imagination; the imagery and metaphors derived from the language of flowers were incorporated into his theory of masculinity, equated with aggressive sexuality, differentiated from femininity, characterized by submission and masochistic fantasies. By presenting details of Freud's experience from his autobiographic writings, the paper demonstrates his use of his personal struggle with adolescent fantasies in drawing generalizations about the role of fantasy in mental life.