Juvenal wrote this proverb in his Satires and it is applicable to modern times; such as, a reference to situations in which there is little confidence in the people appointed to positions of trust; for example, those who are duty-bound to watch over public funds.

Juvenal may also have been referring to the problem of hiring guards to prevent infidelity among women whose husbands were out of town. Another interpretation could be the advice to avoid assigning a fox to guard the henhouse.