 Complete the following phrase:  The poemwhich most speculate proceeded in chronological orderwas likely divided into triads with a concentric, symmetrical structure. In the first seven books, Ennius wrote about mythical and historical past episodes, whereas in the following eight and eventually, eleven, he wrote about contemporary events. Although most of the poem has been lost, there is a traditionalalbeit conjecturedorganization for the book. Books 13 cover the end of the Trojan War in 1184 BC, to the reign of the last king of Rome, Lucius Tarquinius Superbus 535509 BC. Books 46 revolve around the early Roman Republic up until the Pyrrhic War in 281271 BC. Books 79 deal briefly with the First Punic War 264241 BC before covering the Second 218201 BC in more detail. Books 1012 focus on the Second Macedonian War. The ending to these three books is unclear; Ennius might have concluded with an epilogue, or detailed Romes campaign against Antiochus III the Great, 192 BC. Books 1315 detail the 