On the Atlantic's terrific web site, I just found an essay from 2006 that looked back at some of the advice given by writers throughout the magazine's history. It includes thoughts from Francine Prose, Wallace Stegner, and John Kenneth Galbraith, who wrote in 1978:

"All writers know that on some golden mornings they are touched by the wand—are on intimate terms with poetry and cosmic truth. I have experienced those moments myself. Their lesson is simple: It's a total illusion. And the danger in the illusion is that you will wait for those moments. Such is the horror of having to face the typewriter that you will spend all your time waiting. I am persuaded that most writers, like most shoemakers, are about as good one day as the next (a point which Trollope made), hangovers apart. The difference is the result of euphoria, alcohol, or imagination. The meaning is that one had better go to his or her typewriter every morning and stay there regardless of the seeming result. It will be much the same."