 It contains some brief astronomical notes, but its more significant portions discuss the religious festivals of the Roman religion, the rites performed upon them, and their mythological explanations.These explanations preserve much mythological and religious lore that would have otherwise been lost.The first book opens with a prologue which contains a dedication (1–62) of the poem to Germanicus, Ovid's recusatio, and a description of the poem's theme as the Roman calendar, festivals, and annual astronomical events, followed by a discussion of Romulus' and Numa's invention of the Roman calendar.