This is a great example of the much documented issue of lack of documentation
Well put! Exactly.
Remember, too, that when you say...
Can any significance be derived from the fact that he wrote that peace of mind and freedom from pain imply a state of rest, whereas joy and delight are seen to consist in motion and activity?
That's not exactly what Epicurus said. That's an extrapolation and Interpretation of:
"ἡ μὲν γὰρ ἀταραξία καὶ ἀπονία καταστηματικαί εἰσιν ἡδοναί: ἡ δὲ χαρὰ καὶ ἡ εὐφροσύνη κατὰ κίνησιν ἐνεργείᾳ βλέπονται."
That whole "which imply a state of rest" is contained in καταστηματικαί. The only thing that we can be sure is that that first sentence reads:
"For ataraxia and aponia are 'katastēmatikai' pleasures..."
What did Epicurus mean by katastēmatikai pleasures?? That's the rub. LSJ says
καταστηματικός , ή, όν,
A.pertaining to a state or condition
as well as, in relation to musical instruments, "calming"
Henry George Liddell, Robert Scott, A Greek-English Lexicon, Κκ , κατάσσυ^τος , καταστηματικός
That's a LOT of commentary and Interpretation that gets thrown about from "scholars" and "experts " and a LOT of it gets filtered through a Platonic lens before it ever settles on Epicurus.
If this is a direct quote from Epicurus from his On Choices (and Rejections), then there's no doubt Epicurus had words to say about different kinds of pleasure. He says it right there:
ἀταραξία καὶ ἀπονία are this type of pleasures (ἡδοναί hēdonai); χαρὰ and ἡ εὐφροσύνη are ....
βλέπονται "seen" possibly "experienced? exist?"
Henry George Liddell, Robert Scott, A Greek-English Lexicon, βλέπω
κατὰ κίνησιν ἐνεργείᾳ (kata kinēsin "through/by way of motion" energeiai "activity, etc.")
http://www.perseus.tufts.edu/hopper/text?do…ntry=e)ne/rgeia Note that LSJ has it defined as "the opposite of ἕξις" which is "a state or habit of mind" which seems exactly to me what the katastematic Pleasures point to: a state of being. So that dichotomy is reinforced using ἐνεργείᾳ...