The dedication to My Antonia reads:
TO CARRIE AND IRENE MINER In memory of affections old and true
Optima dies... prima fugit VIRGIL
Writers usually choose to dedicate books to people who have had significant influence on their personal or artistic lives. A dedication can be a mark of gratitude or admiration.
The quotation from Virgil, "Optima dies prima fugit" or "the best days are the first to flee" (or "the most fleeting"; cf. Horace, "Eheu, Postume, fugace, fugace"), suggests that the novel is about memories of an idyllic past which has disappeared. This fits the theme that the prarie communities of Cather's choildhood have disappeared, and moreover she herself is no longer the innocent rural child of her past. The narrator's journey to the past echoes this theme, in that Antonia is grown and married, and he cannot retrieve the relationship or circumstances of his past.