Passing back through the historic age of iron and the sub-historic age of bronze, we come to a time, about four thousand years ago, when there were no men in the west of Europe who made use of metals at all, although, for a thousand or two years earlier, men were using bronze and copper in the East. European races immediately before the first use of metals made beautiful implements of stone (chiefly flint), and finished them by grinding and polishing them. These men are spoken of as Neolithic men, or men of the Neolithic period. They had herds and cultivated crops, and they built after a fashion rough houses in wood and tombs and temples with great slabs of stone. They made pottery and woven cloth. The animals and plants of Europe were the same in those late prehistoric times as they are to-day. The Lake dwellings of Switzerland belong to this epoch and yield us their remains as evidence. The men had very nearly the same set of domesticated animals as we have to-day, but they had no skill in carving outlines of animals. Their only decorative work consisted of parallel lines, straight or in zigzags or in circles, graven on the great stone slabs which they erected. We can trace them back to some seven thousand years B.C. and then comes a huge gap–we do not know how many thousand years–in our evidence as to what was going on in this part of the world. We find convincing proof that before this interval the climate was much colder than it is to-day, and that the land surface of Europe was in many respects very different from what it became later. Britain was continuous with the Continent. There were in that remote period human tribes spread over the less frigid valleys of Europe. They had no fields, no herds; they fed on the roasted flesh of the animals they chased and on the fish they speared, and on wild fruits and roots. They dwelt chiefly, if not wholly, in caves, probably also in skin tents, but they did not build either in wood or in stone. The age which we thus reach is called the Palæolithic, or "ancient" Stone age, because men made use of stone, which they chipped into shape, but, unlike the Neolithic people, never polished it. We find enormous numbers of these rough or Palæolithic stone implements both in caves and in the gravels deposited in the ancient beds of rivers. They are so abundant as to prove the existence of a very considerable human population in the remote ages when they were fashioned and used. The changes which have taken place and the time involved since some of these Palæolithic implements were made and used may be guessed at (but cannot be definitely calculated) from the fact that the beds of the rivers which formed the gravel terraces in which they are found in England were, in many cases, from one to six hundred feet above the level of the present rivers. The land surface has risen and the rivers have simultaneously excavated deep and wide valleys leaving terraces of gravel high up on their sides. These show