...as we proceed to higher and higher levels of expertise, and as the stakes get higher and higher, the agonies of excellence reappear in new and frightening ways. A tiny minority gets through to the top, to memorable excellence or profound understanding. The rest of us stop at stages along the way, perhaps for a temporary rest, perhaps for a period of reassessment. But once we stop, we are unlikely to start up again. Security is suddenly far sweeter than enterprise. The sufferings of the ascent, so long endured by insuppressible aspiration, suddenly seem pointless.