《汉书·传·董仲舒传》
所以阳常常处在盛夏，把生育养长作为自己的事；阴经常处在严冬，积聚在空虚不起作用的地方。
是故阳常居大夏，而以生育养长为事；阴常居大冬，而积于空虚不用之处。
Therefore, Yang is often in the height of summer, when it takes upon itself the task of birth and growth; and Yin is often in the depths of winter, stored up in empty, inactive places.