Jeremy Bentham

Take any two persons, A and B, and suppose them the only persons in existence:—call them, for example, Adam and Eve. Adam has no regard for himself: the whole of his regard has for its object Eve. Eve in like manner has no regard for herself: the whole of her regard has for its object Adam. Follow this supposition up: introduce the occurrences, which, sooner or later, are sure to happen, and you will see that, at the end of an assignable length of time, greater or less according to accident, but in no case so much as a twelvemonth, both will unavoidably have perished.

Jeremy Bentham, Constitutional Code, Oxford, 1983, vol. 1, p. 119