Diderot defends what novelists do, in his essay "In Praise of Richardson":
You accuse Richardson of boring passages! You must have forgotten how much it costs in efforts, attentions, moves to make the smallest undertaking succeed, to end a lawsuit, to conclude a marriage, to bring off a reconciliation. Think what you like of these details; but I'm going to find them interesting if they're true, if they bring out passions, if they show people's characters.
They're commonplace, you say; they're what one sees every day! You're mistaken; they're what takes place in front of your eyes every day that you never see. Be careful; you're putting the greatest poets in the dock, under Richardson's name. A hundred times you've seen the sun set and the stars rise; you've heard the countryside echo with song breaking forth from birds; but who among you has felt that it was the noise of the day that rendered the silence of the night so touching? All right, well, there are moral phenomena that exist for you the same way physical phenomena do: outbreaks of the passions have often reached your ears; but you are very far from knowing all that there is in the way of secrets in their tones and in their expressions. There's not a single one that doesn't have its own physiognomy; all these physiognomies appear in succession on a face, without its ceasing to be the same; and the art of the great poet and of the great painter is to show you a fugitive circumstance that had escaped your notice.