Françoise Sagan, The Art of Fiction No. 15 (1956)
Did you find it difficult to switch from the first person of Bonjour tristesse to the third-person narrative of Un Certain sourire? There are those which simply tell a story and sacrifice a great deal to the telling—like the books of Benjamin Constant, which Bonjour tristesse and Un Certain sourire resemble in construction. Yes, I would like to write—in fact I’m now planning—a novel with a larger cast of characters—there will be three heroines—and with characters more diffuse and elastic than Dominique and Cécile and the others in the first two books.
Source: www.theparisreview.org