For the world is so constituted that everything which exists at present has existed before, under different names, in different times and different places. Thus everything that has existed in the past is partly in existence now and partly will exist at other times, returning into being every day, but in different disguises and in different colors, so that without a very good eye one takes it for new and fails to recognise it. But someone with a sharp eye, who knows how to compare and contrast one event with another and consider what the substantial differences are and which matter less, easily recognises it and with calculations and measurements of past events knows how to calculate and measure wuite a lot of the future.