"When any body is strained beyond a certain amount and then released, it fails to return completely to its original form and volume or it retains a permanent set. The largest strain of any kind which a body may undergo and still completely recover from when released is called the limit of elasticity for that form of strain, and the corresponding stress is called the limiting stress. The limit of elasticity is... widely different for different substances. Thus, rubber may be greatly extended and yet recover, while the limit for glass and ivory is very small. ... Within the limit of elasticity a simple law, first stated by Hooke in 1676 and known as Hooke's law, holds, namely, "stress is proportional to strain." (Hooke's statement in Latin was "Ut tensio sic vis.") Hooke illustrated his law by various cases of strain, such as the stretching of a spiral spring and of a wire, the bending of a beam, the twisting of a wire, and so on."