《黄帝内经·素问·本病论》
于是有升之不前而降之不下的；有降之不下而升之至天的；有升降俱不得前进的，作出这样分别，乃是由于在气交的各种变化之中，变化之中存有差异，各自的常态即不相同，因此，发生的灾害也就有轻有重了。
于是有升之不前，降之不下者；有降之不下，升而至天者；有升降俱不前，作如此之分别，即气交之变，变之有异，常各各不同，灾有微甚者也。
So there are those who do not rise and do not fall; those who do not fall and rise to the sky; those who rise and fall can't move forward. The reason for making such a distinction is that there are differences in the various changes of qi exchange. Their normal states are not the same, so the disasters that occur are also more or less severe.