Response or Comment
Where the law creates a duty or charge and the party is disabled to perform it without any default in him, and hath no remedy over, there the law will excuse him. * * * But where the party by his own contract creates a duty or charge upon himself, he is bound to make it good, if he may, notwithstanding any accident by inevitable necessity, because he might have provided against it by his contract. Paradine v. Jane, Aleyn, 26, a case not really involving a question of impossibility. Most discussions of the effect of subsequent impossibility of performance upon contractual obligations start with this often quoted statement.
Aigler, Ralph W. "Subsequent Impossibility as Affecting Contractual Obligations." Mich. L. Rev. 17 (1919): 689-92.