Even in the very simplest and most primitive form of roadwork material enters. There is always the necessity of hardening some bit of soft ground or of smoothing some bit of unevenness, and from the beginning of travel you have had the transportation of material to the established road for the improvement of its surface, for the bridging of its water obstacles or flooring of fords, for the making of its causeways over marshes. In what may be called the middle period of road construction--that is, in periods of high civilisation, but civilisation not provided with modern instruments--the immediate neighbourhood of material introduced a considerable modifying factor into the trajectory of a road. This was often masked, from the fact that the same soil which provided good going and therefore developed early tracks usually also provided, in the nature of things, good material for hardening the surface, for the building of causeways, and even for the throwing of bridges. It was also masked by the fact that the bridge, if it were to be built of wood, could get its material from a considerable distance, as the river was its avenue of supply. But though transport of material has gone through a revolution in the last hundred years, and material for road-making is now brought half across the world (_e.g._ Colonial wood pavement), yet the way neighbourhood of material tells can still be seen everywhere upon the road map of Europe. Thus the absence of main roads in the Fens for centuries was not only due to the necessity of continual artificial work, embankments, and bridges (this would not have deterred the Roman road-makers nor the great effort of the early Middle Ages from attempting a full network of roads). It was rather due to the absence of hard material. And you have the same phenomenon in the Landes of South-western France, where to this day only one great road serves an immense district whose loose and sandy soil fails to provide a cheap and sufficient material. The traveller in Holland notices the same thing: here are roads ultimately depending upon brick paving and narrow, where, had there been abundant material available, they would have been broad, for they had to carry a great deal of traffic. The alternative water traffic by their side was largely developed by the difficulty of making the road.