Definition of "mutability"

He did indeed account somewhat unfairly for this sudden change; for besides some hard and unjust surmises concerning female fickleness and mutability, he began to suspect that he owed this want of civility to his want of horses […]

1749, Henry Fielding, The History of Tom Jones, a Foundling, volumes (please specify |volume=I to VI), London: A[ndrew] Millar, […]

There rise authors now and then, who seem proof against the mutability of language, because they have rooted themselves in the unchanging principles of human nature.

1819 November 10, Geoffrey Crayon [pseudonym; Washington Irving], “The Mutability of Literature”, in The Sketch Book of Geoffrey Crayon, Gent., number IV, New York, N.Y.: […] C. S. Van Winkle, […], page 23