This book is a fine, well-illustration retrospective and current update on one of the pioneers of Op Art and the eternal power of geometry and the sensuality of the curve. Whether circle arrangements, stripe patterns, or lacing of mechanically drawn curves, Riley's paintings are a feast for the eyes. But this is not simple geometric painting or familiar spatial illusions (as in the early years of Op). There is a complexity that is yet peaceful. The rich colors are joyful. Underappreciated in the United States, Riley's work can inspire a new look at the solid form.