In only one considerable group of causes [cause] has the defendant been held liable where unforeseeable intervening causes have brought about unforeseeable results [result]. It is quite often said in the cases that when the negligence of a defendant "concurs" with an act of God, which is to say an unforeseeable force of nature, the defendant is to be held liable. Sometimes it is a problem what this is supposed to mean. In most of the cases the result brought about by act of God is the same as that threatened by the defendant's negligence, so that the defendant is held liable for the foreseeable result. Where a totally different result is brought about, most cases agree that there is no liability, even though there is concurrence in causation. The exceptional cases are those in which a carrier delays goods in transit, and during such delay the goods are destroyed by an unforeseeable flood or other force of nature. Here a number of courts have held the carrier liable.