intimate society of friends. Tetrapharmakos Tetrapharmakos, or "The four-part cure", is Philodemus of Gadara's basic guideline as to how to live the happiest possible life, based on the first four of doctrines. This poetic doctrine was handed down by an anonymous Epicurean who summed up Epicurus' philosophy on happiness in four simple lines: Letters of Epicurus Three letters of Epicurus are preserved by Diogenes Laertius. Letter to Herodotus Epicurus' Letter to Herodotus (not the historian) was written as an introduction to Epicurean philosophy and method of studying nature. It included the most complete detail of the ancient conversations that led to the development of atomist theory, a doctrine of innumerable worlds, and an explanation of the phenomenon of time that posits an early form of relativism. Epicurus' Letter to Herodotus appears to be a summary of On Nature, books I–XIII. Letter to Menoeceus Epicurus' Letter to Menoeceus is a summary of his ethical teachings written in the epistolary literary style, and addressed to a student. It addresses theology, the hierarchies of desires, how to carry choices and avoidances in order to achieve net pleasure, and other aspects of Epicurean ethics. Epicurea The Epicurea is a collection of texts, fragments, and testimonies by Epicurus that was collected by Hermann Usener in 1887. This work features a collection of writings by Epicurus that explain the values and beliefs of Ancient Epicurian philosophy. Other ancient testimonies One of the earliest Roman writers espousing Epicureanism was Amafinius, although his work has not survived. Other adherents to the teachings of Epicurus included Lucretius, who wrote the poem De rerum natura about the tenets of the philosophy. The Epicurean philosopher Philodemus of Gadara, until the 18th century only known as a poet of minor importance, rose to prominence as much of his work, along with other Epicurean material such as the lectures of Zeno of Sidon, was discovered in the Villa of the Papyri. Another major source of information is the Roman politician and philosopher Cicero, although he was highly critical, denouncing the Epicureans as unbridled hedonists, devoid of a sense of virtue and duty, and guilty of withdrawing from public life. Another ancient source is Diogenes of Oenoanda, who composed a large inscription at Oenoanda in Lycia. Diogenes Laërtius reports slanderous stories, circulated by Epicurus' opponents. Legacy Later antiquity The early Christian writer Lactantius criticizes Epicurus at several points throughout his Divine Institutes and preserves