These considerations also raise a presumption that peoples derived by the blending of several stocks may be expected to have progressed further in civilisation and in national growth than those of purer stock; and that, while the racial purity of a people may give stability, such a people will be liable to arrest and crystallisation of civilisation at an early stage, before culture is sufficiently advanced to render possible a highly developed national life. These indications are well borne out by a survey of the peoples of the world. We may see here, in all probability, one of the main causes of the early crystallisation of Chinese civilisation. Homogeneity and racial purity have produced extreme stability, but at the cost of the variability which produces great and original minds, and, therefore, at the cost of capacity for national progress beyond an early stage. CHAPTER X OTHER CONDITIONS OF NATIONAL LIFE In the two foregoing chapters, we have considered in relation to the life of nations three principal conditions essential to all collective mental life and action, even that of the unorganised crowd—namely, homogeneity, free communications and leadership. We have now to consider other conditions which may render the collective mental processes of nations very different from, and superior to, those of a mere crowd. In considering a patriot army as exemplifying collective life of a relatively high level, we distinguished five principal conditions that raise it above the level of the mental life of the crowd, in addition to one which is present in some crowds. This last was a common well-defined purpose present to, and dominant in, the minds of all individuals. It is this condition mainly that renders the collective mental life of such an army so simple, so relatively easy to understand, and so extremely effective.