上品无寒门

From a memorial by the Western Jin official 刘毅 (died 285), recorded in his biography in the 晋书, which urged an end to the Nine-Rank system, 九品中正制: 上品无寒门，下品无势族 'no humble families in the top grades, no powerful clans in the bottom ones'. The officials who did the grading came from the great families, and family standing came to decide the grades.

寒门, literally 'cold gate', is a family without rank or wealth, and 上品 are the top grades. The line is still quoted about any field where family background decides who reaches the top. Its hopeful counterpart is the saying 寒门出贵子 'poor homes can raise great sons'.