But there is no difference in principle between the case where a natural cause or physical factor intervenes after the act in some way not to be foreseen, and turns what seemed innocent to harm, and the case where such a cause or factor intervenes, unknown, at the time; as, for the matter of that, it did in the English cases cited. If a man is excused in the one case because he is not to blame, he must be in the other. The difference taken in Gibbons v. Pepper, cited above, is not between results which are and those which are not the consequences of the defendant's acts: it is between consequences which he was bound as a reasonable man to contemplate, and those which he was not. Hard spurring is just so much more likely to lead to harm than merely riding a horse in the street, that the court thought that the defendant would be bound to look out for the consequences of the one, while it would not hold him liable for those resulting merely from the other; [94] because the possibility of being run away with when riding quietly, though familiar, is comparatively slight. If, however, the horse had been unruly, and had been taken into a frequented place for the purpose of being broken, the owner might have been liable, because "it was his fault to bring a wild horse into a place where mischief might probably be done." To return to the example of the accidental blow with a stick lifted in self-defence, there is no difference between hitting a person standing in one's rear and hitting one who was pushed by a horse within range of the stick just as it was lifted, provided that it was not possible, under the circumstances, in the one case to have known, in the other to have anticipated, the proximity. In either case there is wanting the only element which distinguishes voluntary acts from spasmodic muscular contractions as a ground of liability. In neither of them, that is to say, has there been an opportunity of choice with reference to the consequence complained of,--a chance to guard against the result which has come to pass. A choice which entails a concealed consequence is as to that consequence no choice.