build on sand

Idioms and Phrases

Use an unstable foundation, as in If you buy nothing but high-risk stocks, your portfolio will be built on sand . This metaphor appears in the New Testament, where Jesus likens those who do not heed his sayings to a foolish man who builds his house on sand, which then is washed away by rain, flood, and wind (Matthew 7:24–27). [c. 1600]