Europeans hoping to establish a new life in North American left behind their old communities with unrealistic ideas about their prospects for economic and physical wellbeing. As the devastation caused by Old World diseases decimated Americans Indians, Europeans saw their successful colonization of the New World as proof that indigenous people were actually poorly adapted to the demands of the American environment. The attempt to restrict the art of healing to a small class of elite physicians was offensive to prevailing egalitarian principles and had little impact on the American medical marketplace. Medical practitioners in the new republic could generally be divided into two groups. First, orthodox practitioners claimed to represent the mainstream of learned medical theory and practice going back to Hippocrates. Other than intense antipathy toward what they called "allopathic medicine," irregular practitioners had little in common.