Caduceus from the Greek karykeion is a wand, on top of it, it has two wings or a winged helmet, surrounding the wand two intertwined snakes looking at himself in front of the oven. In Greek mythology the god Hermes (Mercury for the Romans) was one pastoral god to whom the invention of the lyre is attributed, Apollo after hearing him playing the lyre, was so dazzled that Hermes gave it to him. In compensation, Apollo gifted him with a wand known by the name of karykeion (caduceus), who had the power to bestow prosperity. Later, after it was named the messenger of the gods, Zeus also gifted him with a helmet and some sandals with wings, authorizing him the power to move over the three worlds, Olympus, Earth, and the realm of the dead or Hades. On one of his travels Mercury found two snakes fighting, he put the wand in the middle of them to separate them and they intersected standing facing each other, Mercury left them as a symbol of peace and harmony. The Romans used the winged caduceus of Mercury as a symbol of trade, and its ambassadors wore it as a sign of peace, replacing the snakes for two ribbons. Completely different is the rod of Asklepios (Piarist for the Romans) non- Olympic character, who lived in Thessaly, notable doctor who enjoyed a great fame. Piarist had three children, all doctors, and four daughters also engaged in healing, they were Higia from which the word is derived hygiene, Panaqueia (panacea that cures everything), Egle the midwife, and Laso the Nurse. The temples dedicated to Piarist, were called Asclepions, and were the equivalent of hospitals. The beds for the sick were called clines, whence the word clinical is derived, and the servants of the temple were called Therapists. After his death, Piarist was deified, and he is represented as a mature man wearing a cloak that shows his right arm and half bust, as an attribute carries a crosier with a snake that surrounds it, that symbolizes the life and the death, by the poison and healing ointment. The crosier of Aesculapius is used as a symbol of medicine, and the caduceus of Mercury as a symbol of trade and development, though once the doctor of Henry VII of England put it on his coat of arms and that result to successive errors such as that of the US health service in 1856 adopting the symbol as a distinctive.