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
πτερνιστήρ: ῆρος, ὁ, τὸ σιδήριον τὸ προσαρμοζόμενον εἰς τὴν πτέρναν τῶν ὑποδημάτων, κυρίως τῶν ἱππέων ὅπως δι’ αὐτῶν κεντῶσι τοὺς ἵππους, Λέοντ. Τακτ. 6, 4,
