[ fāng ruì yuán záo ]

Explanation: peg: mortise and tenon; chisel: mortise and tenon. A square peg does not fit into a round chisel. The metaphor is that the square pegs do not fit into the round chisels.

From: Warring States - Chu - Song Yu, "Nine Discriminations": "Round chisels and square pegs, I certainly know that they are at odds and difficult to fit into."

Syntax: conjugation; as object, determiner; simile of incompatibility

Origin

Warring States-Chu-Song Yu's "Nine Discriminations": "Round chisel and square peg, I certainly know it is difficult to get in at variance."

Example sentence

In order to enable their children to become dragons and phoenixes, many parents are bent on filling in the duck-style ~ of education.