A Study of the evolution of the flight I faculty—and in particular its effects in I the realm of Nature and in human affairs—reveals analogies which are, perhaps, of more ithan technical interest. When due proportions have been established, it will be seen that the current period in the development of human locomotion is comparable to that very remote epoch during which Nature, having herself solved the problem of flight, exercised the faculty in accord with some inscrutable law. The analogy gains strength from the fact that changes of a profound kind in the conditions of life on this planet followed the evolution of flight in Nature; and that changes no less profound in character have taken, and are now taking, place as the result of man’s so-called ‘conquest of the air’ brought about by technological advancement.