The child's estimates of distance, magnitude, and importance differ from those of the adult. The estimates, however, persist in memory, and we have all discovered, on revisiting familiar scenes of childhood, how exaggerated our childish estimates were when compared with the actual facts. It is this exaggeration of memory, this illusion of the mind's eye, that psychologically is the foundation of the tendency to idealise the past. To us as children the exploits of our elders were marvellous in our eyes; and they remain as marvels in the memory, as marvels, however, which, as all marvels do, belong to the past. The past becomes the wonderland in which were performed the great deeds, not only of our fathers' time, but of the old times before them. The past becomes the poet's treasury, from which he produces things new and old--the abiding-place of all things good and great and beautiful which are not, but ought to be, and therefore once were. To measure progress, as indeed to measure any movement and determine its rate and direction, some fixed points are necessary. As long, therefore, as there is no contemporaneous record of events, fixed in writing, there is no possibility of checking the _laudator temporis acti_ and of reducing the unconscious exaggerations of his memory to their due proportions. But even if there were, in the lowest stages of culture the rate of progress is too slow to be perceptible at the time. In the beginning man is at the mercy of his environment: it is only when he has learnt to modify it to his needs that progress begins to move. And by the time that man has passed from savagery to barbarism, and has emerged from barbarism to civilisation, the conviction that the present and the actual are things of naught as compared with the ideal past, is too intimately inwrought with his religion, his mythology, his philosophy, and the accepted history of his race and its heroic origin to allow him to see facts as they are, or to divine the true trend of human affairs. Further, there is a very practical reason for his looking with suspicion and not with confidence on social changes. It is only as the result of a long course of slow evolution that society has attained to a condition of fairly stable equilibrium. In the beginning society may be compared to a man hanging on for bare life, with a precarious foothold, to the face of a sheer cliff: when the least movement may prove fatal, all movement is dreaded. Thus the characteristic of all early societies is that they are impeded by "the cake of custom" and rigid with the immobility of conservatism.