And Kant had written, at twenty-two, with all the fine enthusiasm of omnipotent youth: “I have already fixed upon the line which I am resolved to keep. I will enter on my course, and nothing shall prevent me from pursuing it.” And so he persevered, through poverty and obscurity, sketching and writing and rewriting his magnum opus for almost fifteen years; finishing it only in 1781, when he was fifty-seven years old. Never did a man mature so slowly; and then again, never did a book so startle and upset the philosophic world.
