Bellow twice

Opening sentence of "The Adventures of Augie March":

“I am an American, Chicago born—Chicago, that somber city—and go at things as I have taught myself, freestyle, and will make the record on my own way: first to knock, first admitted; sometimes an innocent knock, sometimes a not so innocent.”

From a letter to Bernard Malamud, setting out his intentions for "Augie":

“I took a position in writing this book. I declared against what you call the constructivist approach. A novel, like a letter, should be loose, cover much ground, run swiftly, take risk of mortality and decay.”

(h/t Paris Review Daily. If all Bellow's letters are that good.... Seems like a proper book to me.)