Full context:   Defining tragedy is no simple matter, and there are many definitions, some of which are incompatible with each other. Oscar Mandel, in A Definition of Tragedy (1961), contrasted two essentially different means of arriving at a definition. First is what he calls the derivative way, in which the tragedy is thought to be an expression of an ordering of the world; "instead of asking what tragedy expresses, the derivative definition tends to ask what expresses itself through tragedy". The second is the substantive way of defining tragedy, which starts with the work of art which is assumed to contain the ordering of the world. Substantive critics "are interested in the constituent elements of art, rather than its ontological sources". He recognizes four subclasses: a. "definition by formal elements" (for instance the supposed "three unities"); b. "definition by situation" (where one defines tragedy for instance as "exhibiting the fall of a good man"); c. "definition by ethical direction" (where the critic is concerned with the meaning, with the "intellectual and moral effect); and d. "definition by emotional effect" (and he cites Aristotle's "requirement of pity and fear").