Seneca isn't warning us that success requires hard work—that's the comfortable reading. Rather, he's suggesting that the *roughness itself* becomes the material of greatness, not merely an obstacle to it. A musician who plays only pieces within her current ability never develops the calluses, the ear, the intuition that separates competence from mastery; the struggle to interpret Rachmaninoff is what builds her into someone worth listening to. The insight cuts deeper than "pay your dues"—it proposes that without the specific friction of being challenged beyond your present reach, you simply cannot become the person you're aiming to be.