Suffice to say that this piece by Italo Calvino, published in 1986 in the New York Review of Books, is very good indeed:
Let us begin with a few suggested definitions.
1) The classics are the books of which we usually hear people say: “I am rereading…” and never “I am reading….”
This at least happens among those who consider themselves “very well read.” It does not hold good for young people at the age when they first encounter the world, and the classics as a part of that world.
The reiterative prefix before the verb “read” may be a small hypocrisy on the part of people ashamed to admit they have not read a famous book. To reassure them, we need only observe that, however vast any person’s basic reading may be, there still remain an enormous number of fundamental works that he has not read.
Hands up, anyone who has read the whole of Herodotus and the whole of Thucydides! And Saint-Simon? And Cardinal de Retz? But even the great nineteenth-century cycles of novels are more often talked about than read. In France they begin to read Balzac in school, and judging by the number of copies in circulation, one may suppose that they go on reading him even after that, but if a Gallup poll were taken in Italy, I’m afraid that Balzac would come in practically last. Dickens fans in Italy form a tiny elite; as soon as its members meet, they begin to chatter about characters and episodes as if they were discussing people and things of their own acquaintance. Years ago, while teaching in America, Michel Butor got fed up with being asked about Emile Zola, whom he had never read, so he made up his mind to read the entire Rougon-Macquart cycle. He found it was completely different from what he had thought: a fabulous mythological and cosmogonical family tree, which he went on to describe in a wonderful essay.