In traditional European literature, especially fables and fairy tales, a day often equals a year. As a result, although granting Faustus 24 years of as much knowledge as his brain can handle in return for his immortal soul seems like a good deal at first, those 24 years will seem to fly by as quickly as 24 little hours. This merely serves to highlight just how bad of a bargain Faustus has foolishly made. Besides, we also need to consider that life expectancy in Marlowe's day was considerably lower than in ours, so 24 years would have seemed like an eternity to an Elizabethan. Such a vast swathe of time lulls Faustus into a false sense of security, giving him the impression that he has much more time than he really thinks in which to impress the world with his monstrous erudition and intellectual power.