Dr. Elias Petrou, a Greek doctor and physiotherapist, came in 1935 from America where he studied, and with a series of books he wrote and corresponding lectures, he managed to change Greek society within a few years. His own actions, with treatments for people suffering from serious or non-serious illnesses, within a few days and mainly in a natural way, made Greeks believe in him and talk about the new "revolution" of natural hygiene. The therapeutic methods he applied were based on the following: - Fasting for detoxification and correction of bowel function, from where most diseases originate according to natural hygiene and natural therapeutic science. - Fruit therapy to naturally boost the body, treating many diseases but also as a smooth reintroduction to diet after fasting. - Alkaline diet to correct and raise the pH in the blood, as a means of prevention so that we do not get sick. - Physical exercise for the proper functioning of the muscles and the elimination of toxins from the body through burning. - Aerotherapy through our exposure to a clean environment and breathing exercises. - Heliotherapy through our exposure to the sun - sideways in the shade and not directly on the skin - in moderation but steadily throughout the year, so as to acquire the bronze color that is indicative of a healthy person as he said, (not the sickly color of the solarium, nor the excesses of the sun).