What idioms are used to describe the strength of calligraphy, or the profound discussion and insight into things?

perspicacious

This idiom means that the pen goes three points deep into the chessboard. Describing the vigorous brushwork of calligraphy is also a metaphor for profound insights and proper discussion.

This idiom comes from Zhang Tang's book of Huai Yao, Jin Emperor's sacrifice to the northern suburbs, and Wang Xizhi's book's engraving, which is incisive.