Note 131 — Chapter XXIII · PROTAGORAS.
Reading edition
Most critics treat the Protagoras as a composition of Plato’s younger years — what they call his first period — before the death of Sokrates. They fix different years, from 407 B.C. (Ast) down to 402 B.C. I do not agree with this view. I can admit no dialogue earlier than 399 B.C.: and I consider the Protagoras to belong to Plato’s full maturity.