It is a commonplace that, prior to the nineteenth century, communication between one part of Europe and another was never so safe or so rapid as under the Roman Empire. The Roman roads were the cement of the ‘pax Romana,’ and the ‘pax Romana,’ as has been well said, is an ideal which the modern world has not yet been able to realise.

As far as the problems of communication are concerned, the invention of the steam and internal combustion engines establishes an absolutely rigid gulf between the modern age and all previous ages. Before the nineteenth century mechanical transport was unknown, and Napoleon could command no greater facilities than Julius Caesar.

Any consideration, therefore, of the relative efficiency with which the past ages dealt with these questions must stop at the nineteenth century. From then onwards the whole nature of the problem is revolutionised, and resources become available, whose potentialities we have, as yet, hardly begun to realise. Whether they are capable, in concert with other agencies, of giving some kind of unity to a world from which social, moral and political unity have entirely vanished, is a question which the future alone can decide.

It has been suggested, with very probable truth, that the Romans derived many of their ideas of practical statesmanship from their contact with the Persian Empire ; and it is well known that the Persians were magnificent road-makers. For our purpose it is sufficient to note that, under the Roman dominion, the first serious attempt was made to unite Europe, and that as the Imperial frontiers were pushed outward, the continent was gradually covered by a network of splendid roads, many of which are in use at the present day.