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ἴσασι

Τὸ νικᾶν αὐτὸν αὑτὸν πασῶν νικῶν πρώτη τε καὶ ἀρίστη -> The first and best victory is to conquer self.
Plato, Laws 626e

French (Bailly abrégé)

3ᵉ pl. prés. ind. de ἴσημι.

Russian (Dvoretsky)

ἴσασι: 3 л. pl. pf. к *εἴδω.