Its dizzy heights may have passed, but the fad for adult coloring books is far from over. Many trace the origins of such publications to the 1960s, but as Melissa N. Morris and Zach Carmichael explore, the existence of such books goes back centuries. https://publicdomainreview.org/essay/filling-in-the-blanks-a-prehistory-of-the-adult-coloring-craze