Epistulae ad Lucilium 16.7-8
“I consider as my own whatever is well-put by anyone else. Here too is a sentiment expressed by Epicurus: ‘If you live according to nature, you will never be poor; if you live according to fancy, you will never be rich.” For nature desires very little, but the desires of fancy are boundless.”
quicquid bene dictum est ab ullo, meum est. istud quoque ab Epicuro dictum est: ‘si ad naturam vives, numquam eris pauper: si ad opiniones, numquam eris dives.’ exiguum natura desiderat, opinio immensum.
I don’t think what Seneca has in mind is what would call ‘plagiarism’ (the direct use as one own of words written by someone else). Rather, Seneca was writing to his putative correspondent Lucilius as an explicator of Stoic philosophy, and so he not infrequently feels himself compelled to justify his citation of the words of philosophers from other schools. For instance, in Ep. 2.5, he cites Epicurus and parenthetically explains, soleo enim et in aliena castra transire, non tamquam transfuga sed tamquam explorator/For it’s my habit to go over into other people’s camp as well, not as a deserter but as a scout. Both there and here it’s a citation of Epicurus’s words that needs justifying. For a stodgy Stoic, the ideas of the supposedly degenerate Epicurus were particularly touchy (as it were).
Oh,I definitely agree it isn’t plagiarism in the modern sense (although there are some cases that might be ‘Senecan’ in this way). Seneca is definitely not as dogmatic as we might expect…thanks for bringing in this passage and making the point!