The complexity of human nature has always made difficult the task of the literary critic who would attempt to explain the nature of the pleasure that we derive from tragedy. The question has so many connections with speculations outside its own sphere—moral, psychological, political, economic, religious speculations—in short, the entire philosophy of an age—that some simplification, some focal point, is requisite for the historian of ideas who would attempt to record the changes in it through a given age. Since in the eighteenth century the question of tragic pleasure was a live one, in the very forefront of aesthetic speculation, the need for some kind of simplification, some kind of constant against which the evolution of doctrines can be seen, is particularly great. A convenient counter of this kind can be found in the Lucretian “return upon ourselves.”