Thanatos (Greek: Θάνατος), in Greek mythology, is the personification of death. He is a minor figure in Greek mythology, often depicted as a winged youth carrying a sword, a shepherd's crook, or a butterfly-shaped key, which he uses to unlock the souls from the bodies of the dying. Thanatos is the son of the god Hypnos (Sleep) and the goddess Nyx (Night), and he is the twin brother of Hypnos. His Roman equivalent is Mors. The concept of Thanatos has also been used in psychology, notably by Sigmund Freud, who posited a death drive or instinct (German: "Todestrieb") as a fundamental aspect of human psychology. In Hebrew, the concept of death is often translated as מָוֶת (Mavet), though this is not a direct translation of the name Thanatos. In French, Thanatos is sometimes referred to as la Mort, while in Italian, he is known as Tanato.