Palladium
Webster's Dictionary [1]
(1): ( n.) Any statue of the goddess Pallas; esp., the famous statue on the preservation of which depended the safety of ancient Troy.
(2): ( n.) Hence: That which affords effectual protection or security; a sateguard; as, the trial by jury is the palladium of our civil rights.
(3): ( n.) A rare metallic element of the light platinum group, found native, and also alloyed with platinum and gold. It is a silver-white metal resembling platinum, and like it permanent and untarnished in the air, but is more easily fusible. It is unique in its power of occluding hydrogen, which it does to the extent of nearly a thousand volumes, forming the alloy Pd2H. It is used for graduated circles and verniers, for plating certain silver goods, and somewhat in dentistry. It was so named in 1804 by Wollaston from the asteroid Pallas, which was discovered in 1802. Symbol Pd. Atomic weight, 106.2.
Cyclopedia of Biblical, Theological and Ecclesiastical Literature [2]
a name among the ancient Greeks and Romans of an image of Pallas (q.v.), upon the careful keeping of which in a sanctuary the public welfare was believed to depend. The Palladium of Troy is particularly celebrated. According to the current myth, it was thrown down from heaven by Zeus, and fell on the plain of Troy, where it was picked up by Ilus, the founder of that city, as a favorable omen. In the course of time the belief spread that the loss of it would be followed by the fall of the city; it was therefore stolen by Ulysses and Diomede. Several cities afterwards boasted of possessing it, particularly Argos and Athens. Other accounts, however, affirm that it was not stolen by the Greek chiefs, but carried to Italy by AEneas, and the Romans said that it was preserved in the temple of Vesta, but so secretly that even the Pontifex Maximus might not behold it. All images of this name were somewhat coarsely hewn out of wood.
The Nuttall Encyclopedia [3]
A statue of Pallas in Troy, on the preservation of which depended the safety of the city, and from the date of the abstraction of which by Ulysses and Diomedes the fate of it was doomed; it was fabled to have fallen from heaven upon the plain of Troy, and to have after its abstraction been transferred to Athens and Argos; it is now applied to any safeguard of the liberty of a State.
