Advocacy of a non-meat diet, dates back to the middle of the first millennium. In fact, the first recorded teachings of non-meat diets, are the teachings of Pythagoras of Samos around five hundred and thirty b.c. From Plato onward, many Roman and Greek philosophers and writers advocated vegetarianism as an ethical way of life. Vegetarianism has firm roots in religion. It was practiced originally in connection with religious purification rituals.
Many religious groups follow vegetarian diets.
They consider eating flesh gluttonous, cruel and wasteful. In the Roman Catholic Church, Trappist monks have practiced vegetarianism since 1666. Among protestants, the Seventh-Day Adventists observe strict vegetarian guidelines. The Muslim religion in general, does not advocate a flesh-less diet. Hindu and Buddhist sects also consider all animal life sacred and taught that human beings should avoid harming animals.