Thanks, though it feels there that Lucretius is making reference more to the power of wine itself over the mind and body than specifically to the stupor it induces, which is only mentioned alongside its capacity to inflame (iurgia gliscunt).
There's an inconvenient dissimilarity, I agree.
There do seem to be some instances* of the phrase
violentia somni in medieval writing. In the ones I've seen (there are one or two others besides those in the links)
violentia looks like it's being used as a colourless synonym for
vis, but, who knows, maybe there was felt to be a subtly different nuance to it: not just power but irresistible power or something.
Do you think somni is then more likely to modify violentia here or incautum?
If I saw the phrase
ne violentia somni incautum opprimeret in isolation I'd certainly be very tempted to take
incautum with
somni; probably more tempted than I would be to make sense of
violentia somni. Here, though, the sense of the passage as a whole, the syntax and the line break do seem to combine to make that interpretation relatively unlikely.
On a more general note, the emblem is a bit irritating because I can't really see the logic of a leader wanting to prevent himself from falling into a sustained or deep sleep. A leader is as useless to his country while he's half asleep just as surely as when he's deeply asleep. Instead of holding a metal ball that will jolt him awake if he lets go of it, why doesn't he just appoint ministers to be awake while he sleeps who can waken him if the need arises? That way, he'll be a lot more alert when he does have to deal with a crisis the minute after he's woken up.
*p.148 left marginal note, about third of way down -
somni violentiam
p. 336 right column, 11 lines down -
violentia somni
line 1 -
violentia somni