It looks like the Vatican Sayings show simplified versions (or with a more common language in some cases) of some Principal Doctrines. I share a comment that can be interesting from Enrique Álvarez' dissertation: "In both cases [PD 5 and VS 5], we can see how the genre of the florilegium is effective in the transmission of doctrine at the price of rounding off and simplifying the contents. Thus, PD 5 has become an effective aphorism that is a reminder of the reciprocal implication of pleasure an…