Iridology is the science of analyzing the delicate structures of the iris to reveal and locate inflammation in the body and determine how it is manifesting. Nerve fibers in the iris change color and shape to reflect the health of the body and indicate areas of illness or injury.

Bernard Jensen pioneered iridology in the United States and developed a chart that shows regions of the iris mapped to various organs in the body. With this chart, an iridologist can determine a person's constitutional strength, general health status, inherent strengths and weaknesses, and levels of toxic accumulations. It also helps to pinpoint current, chronic, and degenerative health problems and provides guidance for how to improve them with proper nutrition. The chart published in this book remains one of the most comprehensive and accurate indications of the reflexive relationship between the iris and our physical health.