The De rerum natura of Lucretius represents one of the rarest of literary accomplishments, a successful didactic poem on a scientific subject. Epicureanism was the most conservative of the Hellenistic philosophies, but it was not immune to change and modification. While Lucretius was writing, Epicurean philosophers like Philodemus were busy developing the master's doctrine and attempting to answer the objections of their philosophical opponents. Lucretius was familiar with Philodemus or was in any way influenced by his work. More significant is the poet's relationship with contemporary Stoicism. If the central question in Lucretian criticism is the relationship between poetry and philosophy, then it is important to understand the extent to which Lucretius accurately reflects the spirit of Epicurus. The idea of introducing the old Homeric myth of Venus and Mars may in fact have come to Lucretius from Empedodes, who is said to have used it for the two great forces of love and strife which control the Empedoclean universe.