excuse for the nonperformance of duties under a contract, based on a change in circumstances, the nonoccurrence of which was an underlying assumption of the contract, that makes performance of the contract literally impossible From Wikiquote, the free quote compendium
Impossibility is the state of something not being possible. In law, such a state of affairs is a defense to a breach of contract — for example, a contract to pay painters to paint a house may be voided as impossible if the house burns to the ground the day before the painters arrive.
It is not a lucky word, this same impossible; no good comes of those that have it so often in their mouth.
Thomas Carlyle, The French Revolution, A History (1837), Part III, Book III, Chapter X.
The task was impossible, and mortal human beings accomplished nothing but their own destruction when they attempted the impossible.
Tertullian, De Carne Christi, Chapter V, Part II. Called "Tertullian's rule of faith." Also given "Credo quia impossibile." I believe because it is impossible. Same idea in St. Augustine—Confessions, VI. 5. (7). Credo quia absurdum est. An anonymous rendering of the same.
You cannot make, my Lord, I fear, a velvet purse of a sow's ear.