Green Series: Using examples drawn from the art world and modern studio work, this book describes the principles underlying visual balance, symmetry, and the illusion of depth. About the series: These pocket-size volumes make good reference guides for art teachers and students. They are heavily illustrated in color, and are filled with descriptions, technical details, and instructional information. Books fall into four categories. Purple Series books explain art media and techniques. Red Series books describe different art genres and effects. Green Series books illustrate art tools and theory. Yellow Series books recount art history and art movements.