From 《
庄子·
田子方》 (Yan Hui on Confucius): "
夫子奔逸绝尘,
而回瞠若乎后矣" — the master races ahead beyond the dust, and I stare after him. 《
后汉书·
赵咨传》 records a magistrate who escorted Zhao Zi but was left
望尘不及 — watching the dust, unable to catch up. The modern form is
望尘莫及.