Look for a needle in a haystack

Example: “Finding that contact lens in the grass was looking for a needle in a haystack.”

Origin: The image is much older than the wording we use now. Thomas More reached for it in 1532, sending a reader off to hunt a needle in a meadow of hay, and when Shelton translated Don Quixote in 1620 the English form was a needle in a bottle of hay. That bottle is not the vessel: it comes from Old French botel, a bundle, which is why French still says botte de foin. Pottle, a small measure, appears later as a garbling of bottle, and 19th-century proverb dictionaries still record that form. Haystack displaced both only in the 1800s.