“The majority of men in every generation, even those who, as it is described, devote themselves to thinking, live and die under the impression that life is simply a matter of understanding more and more, and that if it were granted to them to live longer, that life would continue to be one long continuous growth in understanding. How many of them ever experience the maturity of discovering that there comes a critical moment where everything is reversed, after which the point becomes to understand more and more that there is something which cannot be understood.”