青出于蓝而胜于蓝

1.Indigo blue is extracted from the indigo plant but is bluer than the plant it comes from.; Blue is extracted from the indigo plant but is bluer than the latter.; know better than one's teacher; excel one's master; progress beyond the ability of one's teacher; Successors excel the predecessor.; The pupil excels the teacher.; The pupil is superior to his teacher.; The pupil learns from and outdoes his teacher.; The pupil surpasses the master.; The worthy disciple excels his masters.