業精於勤 [ㄧㄝˋ ㄐㄧㄥ ㄩˊ ㄑㄧㄣˊ; ye4 jing1 yu2 qin2] mastery of study lies in diligence (idiom). You can only master a subject by assiduous study. Excellence in work is only possible with diligence. Practice makes perfect. ◄ ►