流水不腐,户枢不蠹

liú shuǐ bù fǔ , hù shū bù dù

lit. flowing water does not rot, nor a door-hinge rust (idiom)

fig. constant activity prevents decay

liú

to flow

shuǐ

water

no; not so

decay

,

a household

shū

(bound form) hinge; pivot (usu. fig.)

no; not so

insect that eats into books, clothing etc