Just a thought. I have started reading the De Rerum and there is a dedication to Venus, Goddess of the pro/creative principal amongst other things. Although its customary to have such dedications at the start of long poems, I wonder if something else might not be going on here.
One of Epicurus' main tenets is that the Gods may exist but are in no way connected to our world and pay no attention to our entreaties and cannot harm or heal us, so there is no logical reason to fear them. However, here we have Lucretius at the start of a poem the purpose of which is ostensibly to dispel 'irrational fear of the gods' with a dedication to Venus. Why dedicate a poem to something Epicurus tells us' even if it exists is not at all contingent upon the world of humans and does not pay any attention to us' ?
Perhaps its just literary convention of the day, or is he doing something like 'sweetening the medicine of philosophy'? The dedicatee is one Gaius Memmius and perhaps, Lucretius is trying to win over a sceptical patron, who has professed his fear of or trust in the gods.
There is an article by Gordon Campbell, 'Lucretius and the Memes of Prehistory' (in the External Links at the bottom of this wiki page: http://en.wikipedia.org/wiki/De_rerum_natura ) which throws up the idea that Lucretius is consciously using the conventions of the time in a subtly subversive way. Worth discussing perhaps.