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
ἀμφίστημι (Α)
1. ενεργ. τοποθετώ ολόγυρα
2. παθ. ἀμφίσταμαι τοποθετούμαι, στέκομαι ολόγυρα
3. μέσ. ανιχνεύω, εξετάζω.
[ΕΤΥΜΟΛΟΓΙΑ < ἀμφ(ι) + ἵστημι.