I would agree with Cassius that the prolepseis have to be (to be part of the Canon) pre-rational and provide "building materials" (best phrase I can do right now) for concepts but not concepts themselves. Prolepsis, it seems to me, is a faculty of the mind like sight is for the eyes, taste is for the tongue, hearing is for the ears, etc... Yes, we know they all flow into the brain now, but Epicurus didn't seem to divide up the senses that way.
I've entertained on this forum that the prolepsis of the gods is our innate faculty to feel awe. This also seems at least *partially* substantiated by the use of σέβομαι "to feel awe or fear before a god". For example:
RE: "A Socio-Psychological and Semiotic Analysis of Epicurus' Portrait" by Bernard Frischer
It seems the practices of wearing rings or displaying portrait busts or having cups with Epicurus's picture on them is a physical manifestation of both Seneca's quote "Do all things as if Epicurus were watching" and VS32 Honoring a sage is itself a great good to the one who honors. τοῦ σοφοῦ σεβασμὸς ἀγαθὸν μέγα τῷ σεβομένῳ ἐστί.
σεβασμὸς in modern Greek just means "respect" however, in ancient Greek it was broader: "to be moved by awe, fear, or respect for others or for their…
and
RE: Philodemus On Piety
Quoted in col. 27, On Piety: Epicurus, On Gods (Περί θεών): as being both the greatest thing and that…
Of course, that "faculty" of a prolepsis doesn't help as much when deciding Epicurus's "blessed and incorruptible" vs the mistaken notions specifically the hoi polloi had (LOL... I just like calling them that to keep the original.. better than "the many" or "the crowds".. I'm assuming the Romans would have used "the mob.").
As for the letter to Menoikeus, I think 124 has to be read in the full context, along with 123:
QuoteThe gods do not exist in the way that the 'hoi polloi' believe them to, because they do not perceive what maintains the gods. One is not impious who does not take up the gods of the hoi polloi; but the one who attributes the beliefs of the hoi polloi to the gods.For what they believe are not prolepses but rather the judgements of the hoi polloi concerning the gods which are false, hasty assumptions. So, they believe the greatest evils are brought to the wicked from the gods as well as the greatest aid to the good, because the hoi polloi are believing that the gods accept those who resemble themselves who are similar through all excellences and goodness; all those not of their sort are strange and alien.
So, the hoi polloi's first big mistake is that "they don't perceive what maintains the gods." Plus. their fundamental "false, hasty assumptions" are that the gods bestow favors and punishments. The "gods of the hoi polloi" are the ones that demand sacrifice to keep them on your good side. There's every reason to reject those "gods" because all that is assigning false attributes to the gods, like jealousy, anger, beneficence (to humans), etc. All that has nothing to do with Epicurus's inborn faculty of perceiving the gods' nature. It seems to me that the ONLY things Epicurus is willing to assign to the gods, per Menoikeus's letter, are that they are "blessed" (makarios) and they are "uncorrupted, not liable to corruption or decay, imperishable" (aphthartos).