From the very dawn of history until the first beginnings of mechanism in the eighteenth century, this simple scheme of orders was the universal organization of all but savage humanity, and the chief substance of history until these later years has been in essence the perpetual endeavour of specific social systems of this type to attain in every region the locally suitable permanent form, in face of those two inveterate enemies of human stability, innovation, and that secular increase in population that security permits. The imperfection of the means of communication rendered political unions of a greater area than that swept by a hundred-mile radius highly unstable. It was a world of small states. Lax empires came and went, at the utmost they were the linking of practically autonomous states under a common _Pax_. Wars were usually wars between kingdoms, conflicts of this local experiment in social organization with that. Through all the historical period these two well-defined classes of gentle and simple acted and reacted upon each other, every individual in each class driven by that same will to live and do, that imperative of self-establishment and aggression that is the spirit of this world. Until the coming of gunpowder, the man on horseback--commonly with some sort of armour--was invincible in battle in the open. Wherever the land lay wide and unbroken, and the great lines of trade did not fall, there the horseman was master--or the clerkly man behind the horseman. Such a land was aristocratic and tended to form castes. The craftsman sheltered under a patron, and in guilds in a walled town, and the labourer was a serf. He was ruled over by his knight or by his creditor--in the end it matters little how the gentleman began. But where the land became difficult by reason of mountain or forest, or where water greatly intersected it, the pikeman or closer-fighting swordsman or the bowman could hold his own, and a democratic flavour, a touch of repudiation, was in the air. In such countries as Italy, Greece, the Alps, the Netherlands, and Great Britain, the two forces of the old order, the aristocrat and the common man, were in a state of unstable equilibrium through the whole period of history. A slight change[22] in the details of the conflict for existence could tilt the balance. A weapon a little better adapted to one class than the other, or a slight widening of the educational gap, worked out into historically imposing results, to dynastic changes, class revolutions and the passing of empires.