Throughout the 1950s and early 1960s, Ruth Krauss and Maurice Sendak helped to topsy-turvy and transform the narrative expectations of the picture book with wildly original works like A Hole Is To Dig, A Very Special House, Open House for Butterflies, I Want to Paint My Bathroom Blue, and Charlotte and the White Horse. Ruth Krauss was a remarkable writer, a poet. Her small books are economical, very smart, funny, and magically full of surprise. She was able to give voice to a child's outsized ardor without sounding treacly. She could turn a word game into a philosophical investigation of cause-and-effect without ever losing sight of the fun. She was a nonsense artist, and like other great practitioners of that indispensable art, she knew how to use nonsense as a means of giddy release and also as resistance training for the logic muscle : One's sense of the world is strengthened after successfully surviving assault by nonsense effectively deployed. Sendak responded to Krauss, to her free-associative flow and babble, with quicksilver drawings and watercolors. The best books of their collaboration are like extended jazz duets between two brilliant and inspired artists, each tickling, challenging, and encouraging the other to higher and higher flights of apparently spontaneous invention. As is often the case with revolutionary art, with art that changes its medium, the Krauss and Sendak books, nearly a half-century after they first appeared, are able to startle, as if they still contained the excitement, the mischief, the liberated "why not ?" delight their author and illustrator felt while making them.