The political factors modifying the trajectory of a road (that is, the factors due to man’s social action and not to material causes alone) are three in number. Firstly, the factor of cost--which is, the economic tendency to avoid as far as possible the destruction of old economic values in the making of a road; secondly, legal restraints against the Road’s following its line of least resistance; and thirdly, the presence of a variety of objects to be served, which variety again interferes with the simple rule of finding the trajectory of minimum effort. The first of these political factors, the factor of cost, you find even in the primitive road, which avoids the cultivable land if it can, or crosses it at the narrowest point available, and you find it at the other end of the scale in our complicated modern world, where the Road tends to avoid the destruction of economic values in highly concentrated town life and thus keeps narrow when it is established, and also fails to develop new communications. The effect of this political restraint is constant throughout history, great in all periods, but increasing cumulatively with the increase of wealth and the economic development of society. There follows from this a most interesting historical phenomenon, which I shall deal with at greater length in my second section--“The English Road”--because it would appear to be upon the point of recurring in this island. That phenomenon is the “strangling of communications” in the old age of a wealthy state from the very effect of its wealth. It is a paradox of profound effect which you get over and over again in the history of great mercantile cities: their wealth--which should be their best advantage in developing and changing communication--crystallizes them. Their ways are laid out for a particular phase of traffic. The land on either side of the streets becomes enormously valuable. The traffic changes in character. New ways are demanded by the new conditions, but they are not built because the compensation required for disturbance terrifies the reformer. There follows a phase during which you have heavy congestion of traffic, and then, unless reform comes in time, a succeeding phase of decay. It is very rare in the history of great urban centres to find the problem tackled at the right moment and solved: to find governors of sufficient daring to take the economic plunge. The Government of Napoleon III did so to some extent in the case of modern Paris (though it left a great number of congested streets unrelieved), and there are not a few modern Italian towns where similar action has had its effect: for instance, Bari. But the general rule in history is that a city having reached its highest point of wealth becomes congested, refuses to accept its only remedy, and passes on from congestion to decay.