In its § 142(1) the American Restatement of the Law of Restitution provides that “[t]he right of a person to restitution from another because of a benefit received is terminated or diminished if, after the receipt of the benefit, circumstances have so changed that it would be inequitable to require the other to make full restitution.” The notion that the recipient of an unjustified benefit must in principle return not more than the enrichment that has actually “survived” in his hands, is not only fundamental to the American law of restitution, but can also be found in English and German law.