The grammarian Verrius Flaccus had compiled a prose calendar, with explanations of the established customs pertaining to each day, and it is probably from this that Ovid derived much of his antiquarian lore. The books from which Ovid derived his information are lost, and his work is now one of the chief sources from which we can gain knowledge of Roman ritual, belief, religious antiquities, and even topography, for Ovid frequently mentions the relative positions of temples and other buildings. To the student of Roman life the six books of the _Fasti_ are therefore of great importance. And their importance is not less to the student of Roman poetry, for they teem with beautiful and lively descriptions and interesting stories, and the patriotic sentiments eloquently expressed in several passages show that Ovid was something more than the careless, frivolous writer of corrupt love poems. In beauty of workmanship, vividness of description, and fluent grace of narrative, many portions of the _Fasti_ are equal to any works of Roman literature, not even excepting the _Metamorphoses_ of Ovid himself. [Sidenote: The Metamorphoses.] The fifteen books of the _Metamorphoses_ are Ovid’s greatest achievement. When he began the work we do not know, but, according to his own statement,[82] he had finished it at the time of his banishment, though he had not revised and perfected it to his own satisfaction. In his grief he put the manuscript in the fire and burned it, but several copies must have been made, so the work survived. The opening lines of the poem explain its purpose: Of forms transmuted into bodies new My spirit moves to tell. Ye gods (for ye Did change them), lend my task your favoring breath, And to my times continuous lead the song. This great collection of myths became almost immediately, and has remained ever since, the chief source of popular knowledge of mythology. Poets and artists alike have drawn their conceptions of the ancient gods and heroes from Ovid even more than from Homer. The myths selected are those in which a metamorphosis, or change of form, takes place. Collections of the same sort had been made by several Alexandrian writers; but Ovid was apparently the first to arrange these stories in continuous order from the beginning of the world to his own time. The astonishing skill with which the transition from one tale to the next is accomplished, the rapidity and fluency of the narrative, the abundance of charming descriptive passages, and the never-failing variety of expression, make this one of the most remarkable of poems. The number of stories told is so great that a list of them would be tedious, but a brief mention and characterization of some of the more important among them will serve to show the scope and variety of the work.