《黄帝四经·十大经·观》
黄帝说：天地未生之前，先天一气，看去混混沌沌，窈窈冥冥，浑聚昏暗，如一谷仓。此时阴气阳气未分，无所谓明暗昼夜。阴气阳气聚散未定，所以一切都无法称名。
无晦无明，未有阴阳。阴阳未定，吾未有以名。
Emperor Xuanyuan said: Before the birth of heaven and earth, there was only the innate qi, which appeared chaotic, dark, and gloomy, like a dense valley. At that time, yin and yang qi had not yet separated, and there was no distinction between day and night. The yin and yang qi had not yet settled, and therefore everything was nameless.