In our recent book,Looking at History Through Mathematics (MIT Press, 1968), we discussed two possible mechanisms of a transition of a society from an “arational” behavior, in which most things are accepted uncritically on faith, to a rational behavior, characterized by a critical appraisal of everything. Both mechanisms lead to irreversible changes, which eventually result asymptotically in a complete rationalization of society. In the present paper it is shown that a generalization of the second mechanism may lead to alternations between rational and arational behavior of a society. The reversal from rational to arational behavior is due to the circumstance that for some people hard thinking is either impossible or at least highly unpleasant. It appears, on the basis of the model discussed here, that acomplete rationalization of any society is unattainable.