This Gaius Lucilius (GAY-uhs loo-SIHL-ee-uhs), not to be confused with the satirist Gaius Lucilius (first century b.c.e.), is best known as the friend of Seneca the Younger. Because of his literary talent, political skill, and carefully cultivated friendships with prominent Romans, he rose from obscurity to knight of Rome (eques Romanus). He showed courage and won honor by remaining loyal to the memory of Gnaeus Cornelius Lentulus Gaetulicus, who was executed by Caligula. He held several procuratorships (provincial administrative positions) under the reigns of Claudius and Nero.
The Stoic Seneca addressed Quaestiones naturales (c. 62-64; Natural Questions, 1614), Ad Lucilium epistulae morales (pb. 1917-1925; moral epistles), and De providentia (c. 63-64; On Providence, 1614) to Lucilius, whose own philosophical leanings are unclear. He was certainly an Epicurean as a young man, as Seneca frequently based expositions of Stoicism on his questions or promptings. He may have converted to Stoicism later. He wrote much in both prose and poetry, but except for a few lines of verse quoted by Seneca, none of his works survives.