οὐκ ἂν λάβοις παρὰ τοῦ μὴ ἔχοντος → you can't take from one who doesn't have, you can't squeeze blood out of a turnip, you can't get blood out of a turnip, you can't get blood from a stone, you can't get blood out of a stone
η
μεγάλος λίθος.
[ΕΤΥΜΟΛ. < κοτρώνι + μεγεθ. κατάλ. -α (πρβλ. κεφάλα, κουτάλα)].