In the work Updike was editing before he died, he muses about the "advantages, for a writer, of youth and obscurity."
You are full of material--your family, your friends, your region of the country, your generation--when it is fresh and seems urgently worth communicating to readers. No amount of learned skills can substitute for the feeling of having a lot to say, of brining news. Memories, impressions, and emotions from your first twenty years on earth are most writers' main material; little that comes afterward is quite so rich and resonant.–John Updike, Higher Gossip: Essays and Criticism, 3-4.
By forty, you have probably mined the purest veins of this precious lode; after that, continued creativity is a matter of sifting the leavings. You become playful and theoretical; you invent sequels, and attempt historical novels. The novels and stories thus generated may be more polished, more ingenious, even more humane than their predecessors;
But none does quite the essential earthmoving work that Hawthorne, a writer who dwelt in the shadowland "where the Actual and the Imaginary may meet," specified when he praised the novels of Anthony Trollope as being "as real as if some giant had hewn a great lump out of the earth and put it under a glass case."