ng that the defendant was free from negligence； should have been spread upon the record； in order that the court might judge。 A similar requirement was laid down with regard to the defence of probable cause in an action for malicious prosecution。 /2/ And to this day the question of probable cause is always passed on by the court。 Later evidence will be found in what follows。
There is； however； an important consideration； which has not yet been adverted to。 It is undoubtedly possible that those who have the making of the law should deem it 〃wise to put the mark higher in some cases than the point established by common practice at which blameworthiness begins。 For instance； in Morris v。 Platt； /2/ the court； while declaring in the strongest terms that； in general； ＇116＇ negligence is the foundation of liability for accidental trespasses； nevertheless hints that； if a decision of the point were necessary； it might hold a defendant to a stricter rule where the damage was caused by a pistol； in view of the danger to the public of the growing habit of carrying deadly weapons。 Again； it might well seem that to enter a man's house for the purpose of carrying a present； or inquiring after his health when he was ill； was a harmless and rather praiseworthy act； although crossing the owner's boundary was intentional。 It is not supposed that an action would lie at the present day for such a cause； unless the defendant had been forbidden the house。 Yet in the time of Henry VIII。 it was said to be actionable if without license； 〃for then under that color my enemy might be in my house and kill me。〃 /1/ There is a clear case where public policy establishes a standard of overt acts without regard to fault in any sense。 In like manner； policy established exceptions to the general prohibition against entering another's premises； as in the instance put by Chief Justice Choke in the Year Book； of a tree being blown over upon them； or when the highway became impassable； or for the purpose of keeping the peace。 /2/
Another example may perhaps be found in the shape which has been given in modern times to the liability for animals； and in the derivative principle of Rylands v。 Fletcher； /3/ that when a person brings on his lands； and collects and keeps there； anything likely to do mischief if it escapes； he must keep it in at his peril； and； if he does not do so； is prima facie answerable for all the ＇117＇ damage which is the natural consequence of its escape。 Cases of this sort do not stand on the notion that it is wrong to keep cattle； or to have a reservoir of water； as might have been thought with more plausibility when fierce and useless animals only were in question。 /1/ It may even be very much for the public good that the dangerous accumulation should be made （a consideration which might influence the decision in some instances； and differently in different jurisdictions）； but as there is a limit to the nicety of inquiry which is possible in a trial； it may be considered that the safest way to secure care is to throw the risk upon the person who decides what precautions shall be taken。 The liability for trespasses of cattle seems to lie on the boundary line between rules based on policy irrespective of fault； and requirements intended to formulate the conduct of a prudent man。
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。
Following the same line of thought； the owner of cattle is not held absolutely answerable for all damage which they may do the person。 According to Lord Holt in the alcove opinion； these animals； 〃which are not so familiar to mankind〃 as dogs； 〃the owner ought to confine； and take all reasonable caution that they do no mischief。。。。 But 。。。 if the owner puts a horse or an ox to grass in his field； which is adjoining to the highway； and the horse or the ox breaks the hedge and runs into the highway； and kicks or gores some passenger； an action will not lie against the owner； otherwise； if he had notice that they had done such a thing before。〃
＇120＇ Perhaps the most striking authority for the position that the judge's duties are not at an end when the question of negligence is reached； is shown by the discussions concerning the law of bailment。 Consider the judgment in Coggs v。 Bernard； /1/ the treatises of Sir William Jones and Story； and the chapter of Kent upon the subject。 They are so many attempts to state the duty of the bailee specifically； according to the nature of the bailment and of the object bailed。 Those attempts； to be sure； were not successful； partly because they were attempts to engraft upon the native stock a branch of the Roman law which was too large to survive the process； but more especially because the distinctions attempted were purely qualitative； and were therefore useless when dealing with a jury。 /2/ To instruct a jury that they must find the defendant guilty of gross negligence before he can be charged； is open to the reproach that for such a body the word 〃gross〃 is only a vituperative epithet。 But it would not be so with a judge sitting in admiralty without a jury。 The Roman law and the Supreme Court of the United States agree that the word means something。 /3/ Successful or not； it is enough for the present argument that the attempt has been made。
The principles of substantive law which have been established by the courts are believed to have been somewhat obscured by having presented themselves oftenest in the form of rulings upon the sufficiency of evidence。 When a judge rules that there is no evidence of negligence； he does something more than is embraced in an ordinary ruling that there is no evidence of a fact。 He rules that ＇121＇ acts or omissions proved or in question do not constitute a ground of legal liability； and in this way the law is gradually enriching itself from daily life； as it should。 Thus； in Crafton v。 Metropolitan Railway Co。； /1/ the plaintiff slipped on the defendant's stairs and was severely hurt。 The cause of his slipping was that the brass nosing of the stairs had been worn smooth by travel over it； and a builder testified that in his opinion the staircase was unsafe by reason of this circumstance and the absence of a hand…rail。 There was nothing to contradict this except that great numbers of persons had passed over the stairs and that no accident had happened there； and the plaintiff had a verdict。 The court set the verdict aside； and ordered a nonsuit。 The ruling was in form that there was no evidence of negligence to go to the jury； but this was obviously equivalent to saying； and did in fact mean； that the railroad company had done all that it was bound to do in maintaining such a staircase as was proved by the plaintiff。 A hundred other equally concrete instances will be found in the text…books。
On the other hand； if the court should rule that certain acts or omissions coupled with damage were conclusive evidence of negligence unless explained； it would； in substance and in truth； rule that such acts or omissions were a ground of liability； /2/ or prevented a recovery； as the case might be。 Thus it is said to be actionable negligence to let a house for a dwelling knowing it to be so infected with small…pox as to be dangerous to health； and concealing the knowledge。 /3/ To explain the acts or omissions in such a ＇122＇ case would be to prove different conduct from that ruled upon； or to show that they were not； juridically speaking； the cause of the damage complained of。 The ruling assumes； for the purposes of the ruling； that the facts in evidence are all the facts。
The cases which have raised difficulties needi