To explain the presence of the doctrine of hedonism in Plato's Protagoras (351b–8a), the hypothesis is advanced that the author may have been responding to a suggestion made by Eudoxus of Cnidus that pleasures can be measured in terms of size, number, and intensity. The peculiar ways that Socrates represents these dimensions may indicate that Plato did not fully grasp Eudoxus's suggestion or, conversely, that he saw at once that it was a dead end.