Ok I looked back at 16 and 27 but I still don't see much more there than an allusion or idiom referring to "confronting" a person with the consequences of their thoughts or actions, which seems to me to be a fairly ordinary thing that anyone of any philosophy would do in making a point.
Do you see Philodemus saying more than that in those passages?
What I am reading seems to be something like:
"If someone has a problem confront them by discussing with them the consequences of their actions and fleshing those out in detail."
Ok, if so, that makes sense.
But is there more than that?
Now the specific aspect of telling them to "picture it" might be significant, but wouldn't it be significant only if there is something special in the Epicurean view of how "picturing"relates to thinking?
So I gather that is what we are talking about, some kind of special relationship between thinking and picturing (?)
if so, what is that special insight of Epicurus that makes this significant?