So many discussions go astray because the same words are used in different senses by adherents of different points of view that it seems imperative to start practically every discussion by clarifying the meanings of terms. Yet this problem is easier posed than solved. We in academic life owe understandable allegiance to erudition and to elegance of expression, and all too often we take a definition to be adequate (in the sense of clarifying meaning) if it sounds well. More is required, of course. Clarification of meaning (whether couched in formal definitions or in illustrative examples) takes place only if the terms defined are actually geared to the experience of the people concerned. This is a serious problem, because the experiences of people, although they overlap, can be widely disparate. Particularly among us in academic life the disparity may be quite wide. For our experience is very largely the experience of thinking, and thinking is tempered by language in the broadest sense, that is, by the way ideas are organized. And various ways of organizing ideas are imposed on us by our disciplines. Discipline means constraint. Discipline is essential for any organized activity. And so in academic disciplines, “discipline” means constraint on the mode of thought. It prescribes the repertoire of concepts, the patterns of classification, the rules of evidence, and the etiquette of discourse.