Louise Cowan writes:
How do we recognize a classic? Tradition has held that classics are works of a very high order that touch on matters of immense importance. They are not mere skilled works of whatever category; they establish a category of their own. In fact, when we examine those works that readers have agreed upon as classics, we find a surprisingly constant set of characteristics:
1. The classics not only exhibit distinguished style, fine artistry, and keen intellect but create whole universes of imagination and thought.
2. They portray life as complex and many-sided, depicting both negative and positive aspects of human character in the process of discovering and testing enduring virtues.
3. They have a transforming effect on the reader’s self-understanding.
4. They invite and survive frequent rereadings.
5. They adapt themselves to various times and places and provide a sense of the shared life of humanity.
6. They are considered classics by a sufficiently large number of people, establishing themselves with common readers as well as qualified authorities.
7. And, finally, their appeal endures over wide reaches of time.
Given the rigor of such standards, to call a recent work a classic would seem something of a prediction or a wager. The prediction is that the book so designated is of sufficient weight to take its place in the dialogue with other classics. The wager is that a large number of readers will find it important enough to keep alive. Strictly speaking, as we have indicated, there is no canon of great works, no set number of privileged texts. People themselves authorize the classics. And yet it is not by mere popular taste – by the best-seller list – that they are established. True, books are kept alive by readers – discriminating, thoughtful readers who will not let a chosen book die but manage to keep it in the public eye. They recommend it to their friends, bring it into the educational curriculum, install it in institutional libraries, order it in bookstores, display it on their own shelves, read it to their children. But something more mysterious makes a work an integral part of the body of classics, however well-loved it may be. It must fit into the preexisting body of works, effecting what T. S. Eliot has described as an alternation of “the whole existing order.” The past, he maintains, is “altered by the present as much as the present [is] directed by the past.”
– “The Importance of the Classics,” Invitation to the Classics: A Guide to the Books You’ve Always Wanted to Read.