The same reasoning which would make a man answerable in trespass for all damage to another by force directly resulting from his own act, irrespective of negligence or intent, would make him answerable in case for the like damage similarly resulting from the act of his servant, in the course of the latter’s employment.  The discussions of the company’s negligence in many railway cases would therefore be wholly out of place, for although, to be sure, there is a contract which would make the company liable for negligence, that contract cannot be taken to diminish any liability which would otherwise exist for a trespass on the part of its employees.

More than this, the same reasoning would make a defendant responsible for all damage, however remote, of which his act could be called the cause.  So long, at least, as only physical or irresponsible agencies, however unforeseen, co-operated with the act complained of to produce the result, the argument which would resolve the case of accidentally striking the plaintiff, when lifting a stick in necessary self-defence, adversely to the defendant, would require a decision against him in every case where his act was a factor in the result complained of.  The distinction between a direct application of force, and causing damage indirectly, or as a more remote consequence of one’s act, although it may determine whether the form of action should be trespass or case, does not touch the theory of responsibility, if that theory be that a man acts at his peril.

[91] As was said at the outset, if the strict liability is to be maintained at all, it must be maintained throughout.  A principle cannot be stated which would retain the strict liability in trespass while abandoning it in case.  It cannot be said that trespass is for acts alone, and case for consequences of those acts.  All actions of trespass are for consequences of acts, not for the acts themselves.  And some actions of trespass are for consequences more remote from the defendant’s act than in other instances where the remedy would be case.

An act is always a voluntary muscular contraction, and nothing else.  The chain of physical sequences which it sets in motion or directs to the plaintiff’s harm is no part of it, and very generally a long train of such sequences intervenes.  An example or two will make this extremely clear.

When a man commits an assault and battery with a pistol, his only act is to contract the muscles of his arm and forefinger in a certain way, but it is the delight of elementary writers to point out what a vast series of physical changes must take place before the harm is done.  Suppose that, instead of firing a pistol, he takes up a hose which is discharging water on the sidewalk, and directs it at the plaintiff, he does not even set in motion the physical causes which must co-operate with his act to make a battery.  Not only natural causes, but a living being, may intervene between the act and its effect.  Gibbons v.