Wittgenstein in a lecture once asked his audience to imagine coming across a man who is saying “...5, 1, 4, 1, 3 — finished!”, and, when asked what he has been

Wittgenstein in a lecture once asked his audience to imagine coming across a man who is saying “...5, 1, 4, 1, 3 — finished!”, and, when asked what he has been doing, replies that he has just finished reciting the complete decimal expansion of π backwards. A. W. Moore, The Infinite, Routledge, 1990