On plains, on the other hand, men of genius are rare. Of ancient Egypt, a country of plains, Renan writes: “No revolutionary, no reformer, no great poet, no artist, no man of science, no philosopher, not even a great minister, can be met in the history of Egypt.... In this sad valley of eternal slavery, for thousands of years they cultivated the fields, carried stones on their backs, and were good officials, living well without glory. There was the same level of moral and intellectual mediocrity everywhere.”[243] And the same may be said in our days. At first it seems surprising to see a condition of degeneration, such as genius may be called, developing at spots of maximum salubrity. But if there are anærobic microbes, some are ærobic; many forms of degeneration, such as goître, malaria, and leprosy, have a special habitat. It is evident that we have to reckon with the dynamogenic influence of light, with the stimulating action of the ozonized air of the hills, and of a warm temperature. We may understand this the better since we have already seen that heat augments the creative power of men of genius, and the need of the brain for oxydated blood in order to work is well known. This is confirmed by the fact that in mountains above an elevation of three thousand metres, no man of genius has ever been produced. The great Mexican and Peruvian civilizations flourished on the high tablelands, but, as Nibbi has well shown, they were not born there;[244] in fact, the Mexican civilization is owing to the Toltecas, who came from the east, and the pretended great men of Mexico, including its sixty presidents, were not born on the tableland. The same may be said of many men who were not quite justly termed illustrious, such as Echeveria in painting, Moizzos and Cervantes in botany, and Ixtlihcochitl.[245] Some men of true genius, as Garcilasso dela Vega and Alvares de Vera, were born something below three thousand metres at Quito and Bogota.[246] There is here again a parallelism between genius and insanity. Those who live in mountainous regions are more liable to insanity than the inhabitants of the plains, a fact which has long been embodied in proverbs concerning the air of Monte Baldo, and the madmen of Collio and Tellio. We may recall also the epidemics of Monte Amiata (Lazzaretti), of Busca and Montenero, of Verzegnis; and we may remember, too, that the hills of Judea and of Scotland have produced prophets and half-insane persons gifted with second sight. CHAPTER III. THE INFLUENCE OF RACE AND HEREDITY ON GENIUS AND INSANITY. Race--Insanity--The influence of sex--The heredity of genius--Criminal and insane parentage and descent of genius--Age of parents--Conception.