Mengzi 孟子 6A2 contains the famous water analogy for the innate goodness of human nature. Some evaluate Mengzi’s reasoning as strong and sophisticated; others, as weak or sophistical. I urge for more nuance in our evaluation. Mengzi’s reasoning fares poorly when judged by contemporary standards of analogical strength. However, if we evaluate the analogy as an instance of correlative thinking within a yin-yang 陰陽 cosmology, his reasoning fares well. That cosmology provides good reason to assert that water tends to flow (...) downward, not because of available empirical evidence, but because water correlates to yin and yin correlates to naturally downward motion. Substantiating these contentions also gives occasion to better understand the nature of correlative reasoning in classical Chinese philosophy. (shrink)