In [genre fiction], the relationship between individual work and formula is somewhat analogous to that of a variation on a theme, or of a performance to a text. To be a work of quality or interest, the individual version of a formula must have some unique or special characteristics of its own, yet these characteristics must ultimately work toward the fulfillment of the conventional form. In somewhat the same way, when we see a new performance of a famous role like Hamlet, we are most impressed by it if it is a new but acceptable interpretation of the part. An actor who overturns all our previous conceptions of his role is usually less enjoyable than one who builds on the interpretations we have become accustomed to. But if he adds no special touches of his own to the part we will experience his performance as flat and uninteresting.

[Cawelti] compares the publication of a new detective story by a talented mystery writer with a successful revival of Hamlet; in each case the public wants the new work to exhibit some special character of its own without violating the familiar original form.