History cannot, like physical science, deduce causal laws of general application. All attempts have failed to discover laws of "cause and effect" which are certain to repeat themselves in the institutions and affairs of men. The law of gravitation may be scientifically proved because it is universal and simple. But the historical law that starvation brings on revolt is not proved; indeed the opposite statement, that starvation leads to abject submission, is equally true in the light of past events. You cannot so completely isolate any historical event from its circumstances as to be able to deduce from it a law of general application. Only politicians adorning their speeches with historical arguments have this power; and even they never agree. An historical event cannot be isolated from its circumstances, any more than the onion from its skins, because an event is itself nothing but a set of circumstances, none of which will ever recur.