I want now to launch out without more ado into the full presentation and discussion of a concrete dilemma. It is a dilemma which, I expect, has occasionally bothered all of us, though, in its simplest form, not very often or for very long at a time. But it is intertwined with two other dilemmas, both of which probably have seriously worried nearly all of us. In its pure form it has not been seriously canvassed by any important Western philosopher, though the Stoics drew on it at certain points. It was, however, an ingredient in discussions of the theological doctrine of Predestination and I suspect that it has exerted a surreptitious influence on some of the champions and opponents of Determinism.

At a certain moment yesterday evening I coughed and at a certain moment yesterday evening I went to bed. It was therefore true on Saturday that on Sunday I would cough at the one moment and go to bed at the other. Indeed, it was true a thousand years ago that at certain moments on a certain Sunday a thousand years later I should cough and go to bed. But if it was true beforehand—forever beforehand—that I was to cough and go to bed at those two moments on Sunday, 25 January l953, then it was impossible for me not to do so. There would be a contradiction in the joint assertion that it was true that I would do something at a certain time and that I did not do it. This argument is perfectly general. Whatever anyone ever does, whatever happens anywhere to anything, could not not be done or happen, if it was true beforehand that it was going to be done or was going to happen. So everything, including everything that we do, has been definitively booked from any earlier date you like to choose. Whatever is, was to be. So nothing that does occur could have been helped and nothing that has not actually been done could possibly have been done.

This point, that for whatever takes place it was antecedently true that it was going to take place, is sometimes picturesquely expressed by saying that the Book of Destiny has been written up in full from the beginning of time.