He has settled this matter once and for all; it will not be changed.
Tips
culture
From gong (锣) making: the final hammer strike on a newly cast gong determines its pitch - once struck, the tone is set. The metaphor was fixed in modern Chinese and spread through Liu Shaotang's fiction.
memory
Picture a gong-smith raising the hammer for the last blow - one strike fixes the pitch forever. That final hammer = the final word.
