An excellently organized book by a government scientist relates the meaning and function of eyesight in thirteen chapters that cover the subject from facial expression to what it's like to be blind. To tackle the problem of eye physiology he discusses light sources and characteristics in terms that make the basic principles clear and fascinating. Light travels in waves and can be bent by a lens to focus on a screen- the retin of the eye. Paral and comparisons with other familiar operations, such as photography, further clarify the seeing process so that material becomes almost self-evident as it notes the makeup of the retina, how messages are taken to the brain and there interpreted, the physics of color, binocular vision, what animals see, illusions, and the all important care of the eyes.