 It celebrated, among other things, the 15 BC military victories of his stepsons, Drusus and Tiberius, yet it and the following letter were largely devoted to literary theory and criticism.The literary theme was explored still further in "Ars Poetica", published separately but written in the form of an epistle and sometimes referred to as "Epistles" 2.3 (possibly the last poem he ever wrote).He was also commissioned to write odes commemorating the victories of Drusus and Tiberius and one to be sung in a temple of Apollo for the Secular Games, a long-abandoned festival that Augustus revived in accordance with his policy of recreating ancient customs ("Carmen Saeculare").