Rue has a long history of use in both medicine and magick, and is considered a protective herb in both disciplines. The hardy evergreen shrub is mentioned by writers from Pliny to Shakespeare and beyond, as an herb of remembrance, of warding and of healing. Early physicians considered rue an excellent protection against plagues and pestilence, and used it to ward off poisons and fleas. A Modern Herbal refers to the plant's 'disagreeable odour and flavour', but in truth, the bitterness of the leaves is only evident in large doses. In smaller amounts, it imparts a pleasant, musky flavor to cream cheeses and light meats. Rue was once believed to improve the eyesight and creativity, and no less personages than Michelangelo and Leonardo Da Vinci regularly ate the small, trefoil leaves to increase their own. The legend of rue lives on in playing cards, where the symbol for the suit of clubs is said to be modeled on a leaf of rue. There are concerns that rue is poisonous and can cause violent gastric reactions when taken in large doses. In addition, some people are highly sensitive to the plant's oils and can develop a severe rash when they are exposed to it and then the sun.