“No one can understand history without continually relating the long periods which are constantly mentioned to the experiences of our own short lives. Five years is a lot. Twenty years is the horizon to most people. Fifty years is antiquity. To understand how the impact of destiny fell upon any generation of men one must first imagine their position and then apply the time-scale of our own lives. Thus nearly all changes were far less perceptible to those who lived through them from day to day than appears when the salient features of an epoch are extracted by the chronicler. We peer at these scenes through dim telescopes of research across a gulf of nearly two thousand years. We cannot doubt that the second and to some extent the third century of the Christian era, in contrast with all that had gone before and most that was to follow, were a Golden Age for Britain. But by the early part of the fourth century shadows had fallen upon this imperfect yet none the less tolerable society. By steady, persistent steps the sense of security departed from Roman Britain. Its citizens felt by daily experience a sense that the world-wide system of which they formed a partner province was in decline.”