It has been shown in the first Lecture how this liability for cattle arose in the early law, and how far the influence of early notions might be traced in the law of today, Subject to what is there said, it is evident that the early discussions turn on the general consideration whether the owner is or is not to blame. 2 But they do not stop there:  they go on to take practical distinctions, based on common experience.  Thus, when the defendant chased sheep out of his land with a dog, and as soon as the sheep were out called in his dog, but the dog pursued them into adjoining land, the chasing of the sheep beyond the defendant’s line was held no trespass, because “the nature of a dog is such that he cannot be ruled suddenly.” 3

[118] It was lawful in ploughing to turn the horses on adjoining land, and if while so turning the beasts took a mouthful of grass, or subverted the soil with the plough, against the will of the driver, he had a good justification, because the law will recognize that a man cannot at every instant govern his cattle as he will. 1 So it was said that, if a man be driving cattle through a town, and one of them goes into another man’s house, and he follows him, trespass does not lie for this. 2 So it was said by Doderidge, J., in the same case, that if deer come into my land out of the forest, and I chase them with dogs, it is excuse enough for me to wind my horn to recall the dogs, because by this the warden of the forest has notice that a deer is being chased. 3

The very case of Mason v.  Keeling, 4 which is referred to in the first Lecture for its echo of primitive notions, shows that the working rules of the law had long been founded on good sense.  With regard to animals not then treated as property, which in the main were the wilder animals, the law was settled that, “if they are of a tame nature, there must be notice of the ill quality; and the law takes notice, that a dog is not of a fierce nature, but rather the contrary.” 5 If the animals “are such as are naturally [119] mischievous in their kind, he shall answer for hurt done by them, without any notice.” 1 The latter principle has been applied to the case of a bear, 2 and amply accounts for the liability of the owner of such animals as horses and oxen in respect of trespasses upon land, although, as has been seen, it was at one time thought to stand upon his ownership.  It is said to be the universal nature of cattle to stray, and, when straying in cultivated land, to do damage by trampling down and eating the crops, whereas a dog does no harm.  It is also said to be usual and easy to restrain them. 3 If, as has been suggested, the historical origin of the rule was different, it does not matter.