source

A [https://www.google.com/search?q=%22they+muddy+the+waters+to+make%22+%22deep%22&udm=36&tbs=cdr%3A1%2Ccd_min%3A1800%2Ccd_max%3A2005 google books search with dates restricted to 1800-2005] finds only three sources, the earliest one being [https://www.goog