Jealousy is more than a psychiatric symptom. Its language is universal: the conduct and feelings of the jealous man and woman have repeatedly drawn the attention of the great observers of human nature, the moralists and the philosophers as well as the poets and the novelists. They have, on the whole, described the reaction more successfully than they have defined it. Even the most celebrated definitions—Descartes' “kind of fear related to a desire to preserve a possession” or Spinoza's “mixture of hate and love”, for example— merely illustrate the complexity of a term whose many nuances of meaning can be detected in its roots. The English adjective “jealous” and the noun “jealousy” are derived respectively from the French “jaloux” and “jalousie”, both taken from the old Provençal “gilos”; “gilos” in turn may be traced back to the vulgar Latin adjective “zelosus” which comes from the late Latin “zelus” and so indirectly from the Greek ζηλoς. In its transmission the word has thus been debased. It has ceased to denote “zeal” or “ardour”; the “noble passion” which stood opposed to “envy” for the Greeks has acquired a pejorative quality. In modern German the distinction is preserved verbally, “Eifersucht” having been formed from the original “Eifer” (zeal) and the suffix “-sucht”, which is cognate with “siech”, meaning “sickly”. Amorous jealousy claims associations of its own. During the seventeenth century the French word “jalousie” acquired the meaning of “blind” or “shutter”; in this sense it entered the English language as a noun in the early nineteenth century; the transmutation is thought to have signified a jocular reference to the suspicious husband or lover who could watch unobserved behind the jalousie; the Italian word “gelosia” is used in this way as early as the middle of the sixteenth century. In the Scandinavian languages separate words designate amorous jealousy. (1) The Swedish “svartsjuk”, literally “black sick”, is taken from an old expression which identified jealousy with the wearing of black socks; the Danish “skinsyg”, “afraid of getting skin (a rebuff)”, harks back to an old link of jealousy with skin which may in turn have been connected with hose or socks. (2) The origin of the colours which are traditionally employed to depict jealousy, especially black, yellow and green, is obscure.