Many of Horace's poems also contain much reflection on genre, the lyric tradition, and the function of poetry. "Odes" 4, thought to be composed at the emperor's request, takes the themes of the first three books of "Odes" to a new level. This book shows greater poetic confidence after the public performance of his "Carmen saeculare" or "Century hymn" at a public festival orchestrated by Augustus. In it, Horace addresses the emperor Augustus directly with more confidence and proclaims his power to grant poetic immortality to those he praises. It is the least philosophical collection of his verses, excepting the twelfth ode, addressed to the dead Virgil as if he were living. In that ode, the epic poet and the lyric poet are aligned with Stoicism and Epicureanism respectively, in a mood of bitter-sweet pathos.