When civilizations fail, it is almost always man who has failed ——not in his body, not in his fundamental equipment and capacities , but in his will, spirit , and mental habits.
文明的衰落往往是人们的衰落与失败——并非是身体、机械或能力上的失败，而是意志力、精神以及思维习惯上的失败。

——Philip Lee Ralph, The Story of Civilization
——菲利普·拉夫