To be sure, this mongrel population long remained politically negligible. The Spaniards regarded themselves as a master-caste, and excluded all save pure whites from civic rights and social privileges. In fact, the European-born Spaniards refused to recognize even their colonial-born kinsmen as their equals, and "Creoles"[57] could not aspire to the higher distinctions or offices. This attitude was largely inspired by the desire to maintain a lucrative monopoly. Yet the European's sense of superiority had some valid grounds. There can be no doubt that the Creole whites, as a class, showed increasing signs of degeneracy. Climate was a prime cause in the hotter regions, but there were many plateau areas, as in Colombia, Mexico, and Peru, which though geographically in the tropics had a temperate climate from their elevation. Even more than by climate the Creole was injured by contact with the colored races. Pampered and corrupted from birth by obsequious slaves, the Creole usually led an idle and vapid existence, disdaining work as servile and debarred from higher callings by his European-born superiors. As time passed, the degeneracy due to climate and custom was intensified by degeneracy of blood. Despite legal enactment and social taboo, colored strains percolated insidiously into the creole stock. The leading families, by elaborate precautions, might succeed in keeping their escutcheons clean, but humbler circles darkened significantly despite fervid protestations of "pure-white" blood. Still, so long as Spain kept her hold on Latin America, the process of miscegenation, socially considered, was a slow one. The whole social system was based on the idea of white superiority, and the colors were carefully graded. "In America," wrote Humboldt toward the close of Spanish rule, "the more or less white skin determines the position which a man holds in society."[58]