To fix this degree and the limits to the memory of the past, if it is not to become the gravedigger of the present, we must see clearly how great is the "plastic power" of a man or a community or a culture; I mean the power of specifically growing out of one's self, of making the past and the strange one body with the near and the present, of healing wounds, replacing what is lost, repairing broken moulds. There are men who have this power so slightly that a single sharp experience, a single pain, often a little injustice, will lacerate their souls like the scratch of a poisoned knife. There are others, who are so little injured by the worst misfortunes, and even by their own spiteful actions, as to feel tolerably comfortable, with a fairly quiet conscience, in the midst of them,--or at any rate shortly afterwards. The deeper the roots of a man's inner nature, the better will he take the past into himself; and the greatest and most powerful nature would be known by the absence of limits for the historical sense to overgrow and work harm. It would assimilate and digest the past, however foreign, and turn it to sap. Such a nature can forget what it cannot subdue; there is no break in the horizon, and nothing to remind it that there are still men, passions, theories and aims on the other side. This is a universal law; a living thing can only be healthy, strong and productive within a certain horizon: if it be incapable of drawing one round itself, or too selfish to lose its own view in another's, it will come to an untimely end. Cheerfulness, a good conscience, belief in the future, the joyful deed, all depend, in the individual as well as the nation, on there being a line that divides the visible and clear from the vague and shadowy: we must know the right time to forget as well as the right time to remember; and instinctively see when it is necessary to feel historically, and when unhistorically. This is the point that the reader is asked to consider; that the unhistorical and the historical are equally necessary to the health of an individual, a community, and a system of culture.