How forcible are right words! - How weighty and impressive are words of truth! Job means that he was accustomed to feel their power, and to admit it on his soul. If their words were such, he would listen to them with profound attention, and in silence. The expression has a proverbial cast.
But what doth your arguing reprove? - Or rather, what doth the reproof from you reprove? or what do your reproaches prove? Job professes a readiness to listen to words of truth and wisdom; he complains that the language of reproach used by them was not adapted to instruct his understanding or to benefit his heart. As it was, he did not feel himself convinced, and was likely to derive no advantage from what they said.