Answer: Hofstadter's Fluid Concepts and Creative Analogies by Douglas Hofstadter

On April 5, 1995, John Wainwright was the first non-employee to purchase a book on the newly-launched Amazon.com, and as he states on Quora.com, the book still shows up in his order history.

"I think I ordered the book over a T-1 connection at work," he wrote. "I was working at Kaleida Labs, the Apple/IBM joint venture, at the time."

Photo of book with original packing slip via Quora.com/John Wainwright