But suppose the property has not come back to the hands of the true owner. If the thing remains in the hands of the defendant, it is clearly right that he should surrender it. And if instead of the thing itself he holds the proceeds of a sale, it is as reasonable to make him pay over its value in trover or assumpsit as it would have been to compel a surrender of the thing. But the question whether the defendant has subsequently paid over the proceeds of the sale of a chattel to a third person, cannot affect the rights of the true owner of the [99] chattel. In the supposed case of an auctioneer, for instance, if he had paid the true owner, it would have been an answer to his bailor's claim. If he has paid his bailor instead, he has paid one whom he was not bound to pay, and no general principle requires that this should be held to divest the plaintiff's right. Another consideration affecting the argument that the law as to trespasses upon property establishes a general principle, is that the defendant's knowledge or ignorance of the plaintiff's title is likely to lie wholly in his own breast, and therefore hardly admits of satisfactory proof. Indeed, in many cases it cannot have been open to evidence at all at the time when the law was settled, before parties were permitted to testify. Accordingly, in Basely v. Clarkson, /1/ where the defence set up to an action of trespass quare clausum was that the defendant in mowing his own land involuntarily and by mistake mowed down some of the plaintiff's grass, the plaintiff had judgment on demurrer. "For it appears the fact was voluntary, and his intention and knowledge are not traversable; they can't be known." This language suggests that it would be sufficient to explain the law of trespass upon property historically, without attempting to justify it. For it seems to be admitted that if the defendant's mistake could be proved it might be material. /2/ It will be noticed, further, that any general argument from the law of trespass upon laud to that governing trespass against the person is shown to be misleading by the law as to cattle. The owner is bound at his peril [100] to keep them off his neighbor's premises, but he is not bound at his peril in all cases to keep them from his neighbor's person.