The Kun chapter of the Book of Changes has the line 'treading on frost, solid ice will come'.
Tips
culture
The commentary on this hexagram reads 地势坤，君子以厚德载物 ('the earth lies receptive; the noble person carries all things with deep virtue'). Joined to 自强不息 from 乾卦, it is the motto of 清华大学.
history
Its commentary is also the source of 一朝一夕 'in a single day': crimes like regicide, it warns, grow slowly and are never the work of one morning or one evening.
