263. It is a duty, then, to take care of and to restore what has been entrusted to us. But meanwhile a change comes, either in time or circumstances, Cic. de Off. I. 10. so that it is no longer a duty to restore what one has received. As, for instance, when a man demands back his money as an open enemy, to use it against his country, and to offer his wealth to barbarians. Or, if thou shouldst have to restore it, whilst another stood by to extort it from him by force. If thou restore money to a raving lunatic when he cannot keep it; if thou give up to a madman a sword once put by with thee, whereby he may kill himself, is it not an act contrary to duty to pay the debt? Is it not contrary to duty to take knowingly what has been got by a thief, so that he who has lost it is cheated out of it?