A new broom sweeps clean, but the old broom knows the corners.

This is a traditional proverb commonly attributed to Irish oral culture, contrasting the energy of a newcomer with the seasoned knowledge of someone long in a role. It is often invoked in domestic or workplace settings—when a new manager, official, or family member takes charge and quickly makes visible changes (“sweeps clean”), while long-serving people point out that experience matters for the less obvious details (“the corners”). Like many folk sayings, it circulated widely by word of mouth and appears in proverb collections rather than having a single identifiable first author or moment of utterance.

The proverb acknowledges two truths at once: newcomers can bring vigor, reform, and a willingness to tackle accumulated mess, but veterans possess practical, local knowledge that prevents important details from being missed. “Sweeps clean” praises decisive action and fresh standards; “knows the corners” emphasizes tacit expertise—awareness of hidden problems, exceptions, and the small but consequential tasks that only familiarity reveals. The saying is often used as a caution against overvaluing novelty or assuming that quick early improvements prove lasting competence, while also gently reminding experienced people that fresh eyes can be useful.