From Sima Qian's 《
史记·
汲郑列传》 (Han dynasty). The minister Ji An complained to Emperor Wu:
陛下用群臣,
如积薪耳,
后来者居上 — 'Your Majesty uses officials like stacking firewood; those piled on later end up on top.' Originally a bitter metaphor about promotion by seniority of entry, now used approvingly.