 One of the most notable differences between classical Confucianism and Neo-Confucianism in the Song-Ming period is the prominence of metaphysical speculation in the latter. Many Daoxue Confucians believed that providing an adequate account of the world required that we posit the existence of some things that are formless (xing er shang 形而上) and not readily apparent, the existence of which poses philosophical challenges. Most notably, these Confucians thought we needed something they called Pattern (li, also translated as “principle”) to account for order, unity, and the nature and content of the virtues. They also thought that Pattern is closely linked to human nature, and they were interested in explaining how human cognitive and emotional faculties—what they called the heartmind (xin 心, sometimes translated more simply as “heart” or as “mind”)—can come to recognize and respond appropriately to Pattern.