Oil and water

From Cervantes’s Don Quixote (2.10):

La verdad adelgaza y no quiebra, y siempre anda sobre la mentira como el aceite sobre el agua. [While the truth may run thin, it never breaks, and always rises above falsehood as oil does above water.]

Found via Nuccio Ordine’s The Usefulness of the Useless (2017), a book I discovered by way of Pete Lit’s quotation of a comment from Rob Riemen’s recommendations for the best humanist books of 2017. I’ve used Samuel Putnam’s translation (1949), which I prefer to the unsourced translation in Ordine’s book (“The truth stretches and grows thin, but it does not break and always floats on top of falsehood, like oil on water”). Putnam cites similar proverbs in Italian and Portuguese:

La verità può languire ma non perire. [Truth may languish but not perish.]

A verdade e o aceite andão de cima. [Truth and oil rise to the top.]

Also found in this book
“The man that hath no music in himself”

[The sentence as it appears in the Italian edition of Ondine’s book: “La verità si stira e assottiglia, ma non si rompe e viene sempre a galla sulla bugia, come l'olio sull'acqua.” I suspect that the translator for the English edition translated this translation, not the Spanish text. Neither the Italian nor the English edition includes Cervantes’s sentence in Spanish.]