In the late nineteen-sixties, I was working in rented space on Nassau Street up a flight of stairs and over Nathan Kasrel, Optometrist. Across the street was the main library of Princeton University. Across the hall was the Swedish Massage. Operated by an Austrian couple who were nearing retirement and had been there for decades, it was a legitimate business. They massaged everything from college football players to arthritic ancients, and they didn’t give sex. This, however, was the era when massage became a sexual synonym, and most evenings—avoiding writing, looking down from my window on the passing scene—I would see men in business suits stop, hesitate, look around, and then move toward the glass door at the foot of the stairs. Eventually, the Austrians had to scrape the words “Swedish Massage" off the door, and replace them with a hanging sign they removed when they went home at night. Meanwhile, the men kept arriving at the top of the stairs, where neither door was marked. When they knocked on mine and I opened it, their faces fell dramatically as the busty Swede they expected turned into a short and bearded man.

In this context, I wrote three related pieces that became a book called “Encounters with the Archdruid.” To a bulletin board I had long since pinned a sheet of paper on which I had written, in large block letters, “ABC/D.” The letters represented the structure of a piece of writing, and when I put them on the wall I had no idea what the theme would be or who might be A or B or C, let alone the denominator D. They would be real people, certainly, and they would meet in real places, but everything else was initially abstract.

That is no way to start a writing project, let me tell you. You begin with a subject, gather material, and work your way to structure from there. You pile up volumes of notes and then figure out what you are going to do with them, not the other way around. In 1846, in Graham’s Magazine, Edgar Allan Poe pub...