There is one disease which is widespread, and from which men rarely escape. This disease varies in degree in different men … I refer to this: that every person thinks his mind … more clever and more learned than it is … I have found that this disease has attacked many an intelligent person … They … express themselves not only upon the science with which they are familiar, but upon other sciences about which they know nothing … If met with applause … so does the disease itself become aggravated.