《论衡·卷三·偶会篇》
植物春天发芽，夏天生长，秋天就成熟衰老，正好自然枯萎死去，这时寒气恰巧旺盛，跟它碰到一起。
夫物以春生夏长，秋而熟老，适自枯死，阴气适盛，与之会遇。
Plants sprout in spring, grow in summer, and mature and age in autumn; they naturally wither and die at this time when the cold qi happens to be at its peak and meet them.