Descartes to Mersenne, xii.1638:
[Descartes expresses several dissatisfactions with Fermat, summing up thus:] I have seen many of his writings, in which I have found two or three good things mixed in with many bad ones. Between ourselves, I think of them in the way Virgil thought of Ennius, when he extracted ·little bits of· gold from his works under the title The dung of Ennius [in the background of that slur is a Latin idiom, aurum e stercore = ‘gold from dung’]. But this is between ourselves, because I still want to be his ‘Yours faithfully’ if he wants that.
