Meaning of the word "the mouse that has but one hole is quickly taken" in English

What does "the mouse that has but one hole is quickly taken" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

the mouse that has but one hole is quickly taken

US /ðə maʊs ðæt hæz bʌt wʌn hoʊl ɪz ˈkwɪkli ˈteɪkən/
UK /ðə maʊs ðæt hæz bʌt wʌn həʊl ɪz ˈkwɪkli ˈteɪkən/
"the mouse that has but one hole is quickly taken" picture

Idiom

a proverb meaning that it is risky to rely on only one plan or resource; one should always have an alternative

Example:
I'm applying to several jobs because the mouse that has but one hole is quickly taken.
Always have a backup plan; remember, the mouse that has but one hole is quickly taken.