Anything in the outside world, in all its variations and excesses, its violence and its artificiality could bring on madness, air that was too warm, too cold or too damp, the climate under certain conditions, life in society, 'a love of science or a devotion to letters, both of which are increasingly widespread, a growing luxury that makes life too soft for masters and their servants', the reading of novels, theatrical spectacles, and anything that excited the imagination.