pull the wool over someone's eyes

Example: “Don't let that salesman pull the wool over your eyes.”

Origin: American, first documented in print in November 1835, in a Gettysburg, Pennsylvania newspaper. The most commonly repeated explanation reaches for the woolen wigs fashionable for both men and women in the 1500s and 1600s — pulling one down over the eyes, whether by accident or design, would genuinely blind the wearer to what was happening around them. That theory runs into a real timing problem, though: wig-wearing, especially in America, had largely died out well before 1835, making it an odd source for a phrase appearing right around that same period. A second theory reaches for sheep farming, where wool growing thickly around an animal's eyes can genuinely obstruct its vision. Neither theory is confirmed, and at least one serious source on the phrase's history concludes candidly that the real origin simply isn't known.