The present book demonstrates that the pendulum can be used to detect internal diseases, thus serving as a medical diagnostic tool, and this can be done in a quick, effective, and safe manner. The art of medical diagnosis is truly not so certain and safeguarded against errors that a reliable, easily accessible, and free aid should not be highly welcomed. All internal diseases, both acute and chronic, are often based on infections or fungal infestations, and these are primarily what respond to pendulum examinations. As long as humanity has existed, pendulums have been used extensively for various mystical purposes, and to this day, people pendulate to seek knowledge about the future or the past. Nevertheless, pendulums have not been widely adopted. The ignorance of the underlying nature of this practice remains.