The eye of Horus or the "Utchat" or "Udjat" (sound eye) is a powerful symbol which was believed to offer protection against the "Evil Eye". Horus's right eye is the "Eye of Re" (the sun god) and his left eye is the "Eye of Horus" (and symbolic of the moon). In a battle to avenge Horus's father, Osiris, the god Set plucked out Horus' eye. It was later restored and made whole by Thoth. The udjat was painted on ships and other items needing protection. Jewelled Eyes of Horus were set into sarcophagi to promote vitality in the afterlife. It was also worn to promote health and vitality. The pharmacist's symbol for prescription, "Rx," is derived from this design.