When Russian author Leo Tolstoy was in his 60s, he was asked to list the books which influenced him the most in his career. He responded by grouping the books into three main categories by level of impact: great, v. great, and enormous. Some of his picks:

Matthew’s Gospel: Sermon on the Mount - Enormous

Dickens’ David Copperfield - Enormous

Victor Hugo. Les Misérables - Enormous

Pushkin’s Yevgeny Onegin - V. great

George Eliot. Novels - Great

The NY Times reprinted the list in 1978; here’s the original listing.