aid within the nation, the city or the clan—­we already obtain a perception of the dominating influence of the mutual-aid factor as an element of progress.  But we see also that the practice of mutual aid and its successive developments have created the very conditions of society life in which man was enabled to develop his arts, knowledge, and intelligence; and that the periods when institutions based on the mutual-aid tendency took their greatest development were also the periods of the greatest progress in arts, industry, and science.  In fact, the study of the inner life of the medieval city and of the ancient Greek cities reveals the fact that the combination of mutual aid, as it was practised within the guild and the Greek clan, with a large initiative which was left to the individual and the group by means of the federative principle, gave to mankind the two greatest periods of its history—­the ancient Greek city and the medieval city periods; while the ruin of the above institutions during the State periods of history, which followed, corresponded in both cases to a rapid decay.

As to the sudden industrial progress which has been achieved during our own century, and which is usually ascribed to the triumph of individualism and competition, it certainly has a much deeper origin than that.  Once the great discoveries of the fifteenth century were made, especially that of the pressure of the atmosphere, supported by a series of advances in natural philosophy—­and they were made under the medieval city organization,—­once these discoveries were made, the invention of the steam-motor, and all the revolution which the conquest of a new power implied, had necessarily to follow.  If the medieval cities had lived to bring their discoveries to that point, the ethical consequences of the revolution effected by steam might have been different; but the same revolution in technics and science would have inevitably taken place.  It remains, indeed, an open question whether the general decay of industries which followed the ruin of the free cities, and was especially noticeable in the first part of the eighteenth century, did not considerably retard the appearance of the steam-engine as well as the consequent revolution in arts.  When we consider the astounding rapidity of industrial progress from the twelfth to the fifteenth centuries—­in weaving, working of metals, architecture and navigation, and ponder over the scientific discoveries which that industrial progress led to at the end of the fifteenth century—­we must ask ourselves whether mankind was not delayed in its taking full advantage of these conquests when a general depression of arts and industries took place in Europe after the decay of medieval civilization.  Surely it was not the disappearance of the artist-artisan, nor the ruin of large cities and the extinction of intercourse between them, which could favour the industrial revolution; and we know indeed that James Watt spent twenty or more years of his life in order to render his invention serviceable, because he could not find in the last century what he would have readily found in medieval Florence or Brugge, that is, the artisans capable of realizing his devices in metal, and of giving them the artistic finish and precision which the steam-engine requires.