Interesting to consider:
(1) Is Lucretius appealing figuratively, or literally, to the goddess of pleasure to bring peace to his world?
(2) Is Lucretius also saying that it is true and appropriate BOTH that (a) his own mind cannot work on the poem unburdened by distress, AND (b) that Memmius cannot fail but to participate in the actions of his time?
This is the Bailey translation: https://archive.org/stream/onnatur…age/28/mode/2up
When I have more time I'd like to write a critique of Tennyson's Lucretius; a poetic exploration of St. Jerome's slander. Tennyson's poem bears in interesting ways on the questions you raise. What did Lucretius mean to convey by addressing Venus
In lays that will outlast thy deity?
Lucretius' Venus is a deeply complex figure. The personification of pleasure and sexual generation; the figurative mother of the city of Rome; the vital energy of endless and beginningless re-creation. The sometime lover and sometime rival of human strife, and the endower of human qualities.
Because the world of Epicurean philosophy is a world of human will amidst ceaseless and random Nature, we can infer that the power of Venus to calm the bloodlust of Mars is a token of the power of humans to choose Venus, and not Mars; to—and I'm quoting Tennyson again—keep themselves
from the lust of blood
That makes a steaming slaughter-house of Rome.
The Martin Ferguson Smith translation footnotes this passage "A probable allusion to Memmius’ praetorship of 58 B.C." Wikipedia notes that Memmius was an orator and writer of erotic poetry. All news to me as I've never looked into him before.
So it would seem that Memmius is involved in the events, but there's no indication as to what Lucretius is asking of him other than perhaps to work for peace. But maybe that's obvious. 
I seem to recall that Cicero mentions Memmius' ownership of an Epicurean property in Athens. Theory goes that Lucretius wanted it preserved for the school.
