We are all alive to the fact that there is a lack of harmony between the ancient machinery of our bodies and the modern conditions under which we live, but we are only now awakening to the fact that what is true of our bodies is also true of our minds. In that immense first phase of our history an elaborate mental machinery had been evolved for binding small groups of mankind into social units. This subconscious or instinctive mental outfit, we shall see, is part of the machinery which Nature has employed in the evolution of races of mankind. The mental adaptations which modern man has inherited from the immensity of his past we may briefly describe as part of Nature's tribal machinery. The thesis, then, which I propose to expound to you is that in our modern racial strifes and national agitations we see man's inherited tribal instincts at war with his present-day conditions of life. We have broken up, or are attempting to break up, Nature's ancient tribal machinery and at the present time are striving to replace her designs by others evolved in the minds of modern statesmen and politicians. We moderns are like hill sheep turned into fenced fields with all our wandering instincts still grafted on our original nature. As in them, our instincts are at war with our surroundings. It is the most natural thing in the world that we should blame the barriers which have been set round us because we are scarcely conscious of the inherited predispositions with which Nature encompasses her tribal fields. We cannot understand the nature of our modern racial and national problems until we perceive that in these days we are endeavouring to build a new world out of the wreckage of an old. RACIAL AND NATIONAL PROBLEMS IN THE UNITED STATES OF AMERICA