The ancients said: 'study and then you know your shortcomings; teach and then you know your difficulties.'
Tips
history
From 《礼记·学记》 ('The Record of Rites - On Learning,' compiled Warring States / early Han): 虽有嘉肴，弗食不知其旨也；虽有至道，弗学不知其善也。是故学然后知不足，教然后知困 (Though there be fine food, not eating it you won't know its flavor; though there be the highest Way, not studying it you won't know its excellence. Therefore: study and then you know your insufficiency; teach and then you know your difficulty). Foundational text in the Confucian pedagogy canon.
usage
Canonically paired with 教然后知困. 然后 here is classical 'only then / thereafter,' not the modern 'and then / after that' - the construction means 'not until X does one Y.'
