An author in his book must be like God in the universe, present everywhere and visible nowhere.

Gustave Flaubert (1821-1880) French writer, novelist

Letter to Louise Colet (9 Dec 1852)
    (Source)

In a later letter to Leoroyer de Chanepie (18 Mar 1857), he repeated the sentiment: "The artist must be in his work as God is in creation, invisible and all-powerful; one must sense him everywhere but never see him."