Another striking instance of the incidence of negative selection upon certain mental qualities of a people is afforded by the history of Spain. In the sixteenth century Spain attained to a supreme position of power and grandeur among the nations of the world, such as has been rivalled by Rome alone in all history; and then very rapidly her power decayed, and ever since she has remained one of the most backward of European peoples, contributing little to European culture, to science, art or philosophy, incapable of developing without the aid of foreigners her rich industrial resources, impotent in war, entirely devoid of enterprise and originality. To what is this great change due? It is not due to any adverse change of climate, to devastation by war or plague or famine, nor is it due to any change in geographical or economic relations. Spain remains more happily situated as a centre of commerce than any other country of the world. The mass of the people remains vigorous, proud, and virile. It is the intellect of the nation alone which has decayed, or rather it is the intellectual life of the nation that has become utterly stagnant. Buckle drew a vivid picture of the stagnation of the Spanish intellect and sought the explanation of it in the great power wielded by the Roman Catholic Church, which, he said, had successfully fostered the spirit of protection and superstition, had discouraged every effort of the intellect, and utterly repressed the spirit of inquiry, to the free activity of which all progress of civilisation was, in his opinion, due. Here, again, modern science shows that Buckle was led into error by his ignorance of the importance of the biological factors, the racial qualities and the changes produced in them by selection.