The truly vexing aspect of the Now Problem is conceptual: It is very hard to say what exactly the puzzle consists of. At this point, philosophers and scientists alike typically quote a passage from the fourteenth chapter of the eleventh book of St. Augustine’s Confessions. Here the Bishop of Hippo famously notes, “What then is time? If no one asks me, I know. If I wish to explain it to one that asketh, I know not.”
