[1] The headword (perhaps, though not demonstrably, extracted from the quotation given here) is third person singular, imperfect, of the verb presbeu/w, in sense I.2 at LSJ s.v. See again -- in another context -- at the end of epsilon 3782.
2See generally Diogenes Laertius 1.14 and 2.16 (S. 'introduced' moral philosophy). For the actual phrase given here, see under sigma 829 (but with aorist rather than imperfect).