μεσοῦν

From LSJ

εἰ πλείονα δ' εἰδείης Σισύφου → if you were more intelligent than Sisyphus

Source

Greek > English (Woodhouse Verbs Reversed)

(see also: μεσόω) be at the middle

Lexicon Thucydideum

esse in medio, to be between, 5.20.2, 5.57.1, 6.30.1.