simply must begin here—not only because there is no place else to begin, but because if we think that we will not begin here, it is here that we are thinking that we will not begin. This matter is so important that we must go into a more thorough discussion of skepticism. If credulity was common in the medieval era and superstition in primitive culture, the problem of knowledge from which many modems suffer is skepticism. Proceeding from the true statement that it is the mark of a scholar at times