"Beliefs constitute the basic stratum, that which lies deepest, in the architecture of our life. By them we live, and by the same token we rarely think of them.... One may symbolize the individual life as a bank of issue. The bank lives on the credit of a gold reserve which is rarely seen, which lies at the bottom of metal coffers hidden in the vaults of the building. The most elementary caution will suggest that from time to time the effective condition of these guaranties--of these credences, one might say, that are the basis of credit--be passed in review."