Other remains, not so ancient as these oldest stone implements but still very ancient, are found nearer the surface than the remains of the River-drift Men. They are the remains of people who, like the Drift-men, knew nothing of metals; and they, too, used stone weapons and tools, but these were now better made. They had learned to shape and finish their tools by rubbing, grinding, and polishing them, and they were a much more advanced race of men than the Cave-or Drift-men. These later men, Neolithic Men, did not depend upon the broken and chipped flints which they found lying about on the surface, but discovered that it was better to dig up whole flints, and to select those which were best suited for their purpose, grinding them into the shapes which they wanted, and then polishing them into more shapely and finished weapons. For the most part we have to go to somewhat desolate parts of England to find traces of them now. In fact those traces would long ago have disappeared had they not been in places which were so wild and difficult to get at that it was not worth any man's while to cultivate them. The spade and the plough would very soon remove all traces of them. In fact, the plough _has_ removed many traces of these ancient men, and most of the specimens of their tools and weapons, which you can see in museums, were found by men whilst employed in ploughing and preparing the land for crops. You must not suppose that we can fix a date when these men first appeared, as we can fix an exact date for the landing of Julius Cæsar, or the sealing of Magna Carta. Neither can we say for how many centuries they occupied land in what we now call Britain. It was a long period, at any rate, and during that time their manners and their customs changed very, very slowly.