“Knuth goes on to acknowledge that he doesn’t intend to cut himself off completely from the world. He notes that writing his books requires communication with thousands of people and that he wants to be responsive to questions and comments. His solution? He provides an address—a postal mailing address. He says that his administrative assistant will sort through any letters arriving at that address and put aside those that she thinks are relevant. Anything that’s truly urgent she’ll bring to Knuth promptly, and everything else he’ll handle in a big batch, once every three months or so.”