"The more effective of the two post-coital methods of contraception is to induce menstruation before fertilization or implantation can take place. Many herbal recipes to induce menstruation were taught by Hippocrates, “the father of medicine,” who lived in ancient Athens 460–377 B.C.E. He had gathered his recipes from women whose traditions of medicine were already thousands of years old. Centuries later, some of these methods for inducing menstruation for contraception were published by Peter of Spain before he was made Pope John XXI in 1276. Despite their toxicity, herbs are still used worldwide in attempts to induce menstruation (Riddle, 1992)."