In Greek mythology, Chiron, a wise centaur - half-man and half-horse - taught the art and science of healing to Aesculapius, the god of medicine. Ancient Egyptians worshipped a dog-headed god, Anubis, who was considered physician to the other gods. Physicians in Elizabethan England recommended the close companionship of lapdogs as a remedy for some illnesses. Clearly, the idea of animals as healers of human ailments is not new.  The systematic study of the health benefits of pets began in the 1960s with the work of an American child psychologist, Boris Levinson, who discovered the therapeutic value of animals quite accidentally. One day, he inadvertently left his black Labrador retriever alone in the office with one of his clients, a withdrawn, emotionally troubled young boy. When he returned, Levinson found the boy cuddling and playing enthusiastically with the dog. With the dog as an intermediary, Levinson's therapeutic relationship with the child improved significantly.  Levinson, who first coined the phrase "Pet Therapy," continued to use his dog in his therapy with children for the next 14 years. He also wrote extensively about the potential therapeutic uses of pets, including their value in hospitals and nursing homes. Levinson believed that the key value of pets was their unique capacity to offer unconditional and nonjudgmental affection, which led to feelings of safety and trust. Patients then were often able to transfer these feelings from the pet  The reaction of his colleagues to his theories on pet therapy ranged from ridicule and skepticism to genuine enthusiasm. The latter, it seems, won out. Since the 1970s, research into the physical and psychological benefits of pets has increased dramatically, and what was once the myth of companion animals as healers is now a reality.