If nothing else, Emberley's exercises in black and white magic are an ingenious answer to the industry-wide cutback in color reproduction.
Within a comic strip story of a prince turned into a frog and an incompetent wizard who tries out a bedazzling variety of spells before lighting on the one that can turn him back (meanwhile the prince becomes, briefly, a rabbit, a kangaroo, a grasshopper and a whale), Emberley subjects readers to seven double page eye-whammers to which the Wiz gives such fitting names as rectangle tingle, zig zag zowie and op tickle two.
It's much fun, probably just about where the whole op art game finds its level. Wizard.