Mid story, the Cardinal, who is a major character in the story, lectures Miss Malin about the conceit of wanting to be God, or rather, the conceit of wanting to create a world. Although he doesn't say it, this is what writers do, or try to do. In this way he (and the narrator who created him) lectures all writers in every genre.
"Every human being has, I believe, at times given room to the idea of creating a world himself. The Pope, in a flattering way, encouraged these thoughts in me when I was a young man. I reflected then that I might, had I been given omnipotence and a free hand, have made a fine world. I might have bethought me of the trees and rivers, of the different keys in music, of friendship, and innocence; but upon my word and honor, I should not have dared to arrange these matters of love and marriage as they are, and my world should have lost sadly thereby. What an overwhelming lesson to all artists! Be not afraid of absurdity; do not shrink from the fantastic. Within a dilemma, choose the most unheard-of, the most dangerous, solution. Be brave, be brave! Ah, Madame, we have got much to learn."