be shown to have known it. But when this is once shown, the animal is put upon precisely the same footing as those that usually have such a propensity. The duty to keep cattle from entering upon land or to keep ordinarily ferocious animals from attacking mankind and the duty to keep animals of an ordinarily harmless kind from doing any special harm that they are known to be inclined to do, seem to me to be of precisely the same nature. If the act of the creature is imputed in the one case, it should be in the other; if in either case the liability does not arise from the imputation of the act, it should not in the other be considered as so arising. Hence the trespass test, which separates these duties that obviously belong together, cannot here be relied upon.

However we have something else to guide us. The duty as to animals is clearly analogous to, and indeed appears to me identical with, the duty that a person comes under who has in his control a thing which has a tendency to escape and do damage, such as gunpowder, a reservoir of water or a poisonous tree growing near to his neighbor's boundary line and liable to grow over it. What things fall under this head, and what the duties are of the controllers of them, will be discussed hereafter.1 Speaking generally we may say that a person who has control of such a thing and who knows or ought to know its dangerous nature must prevent it from breaking out and doing the harm that it has a natural tendency to do; or in some of the United States must use due care only to prevent it. If such harm is done by it, the action,. under the common-law system, would not be trespass but case for the omission to do the acts necessary to keep it safely. There can of course be no imputation, because there is no act on the part of the thing. Although an animal may do acts, and there is no theoretical difficulty in imputing such acts to a person and thus holding him answerable for them, which, as we have seen,2 is in fact sometimes done, still it seems likely that the more convenient way is to put the liability for the acts of animals arising: from the possession or control of them on the same ground with. that for other dangerous things.

CHAPTER VI.-DUTIES AND RIGHTS IN GENERAL.

I.-DUTIES.

$108. Meaning of Duty. A person who is commanded or forbidden by law to do an act is under a legal duty to do or not to do it. A legal duty is the condition of one who is so commanded or forbidden.

§ 109. To Whom Duties are Owed. Every duty is owed to some other person who has the power to cause the sanction to be inflicted if the duty is broken. Some duties are owed only to the sovereign; and if these are broken the proceedings to inflict the sanction are taken by the persons who act as the representatives of the sovereign and in his name. Violations of such duties are usually called crimes; but not always, for the sovereign may hold property or enter into contracts, and the duties that then arise in his favor are similar to those arising in favor of private persons in the like situations, and a breach of them may amount to a mere civil injury. Duties owed to the sovereign are often for convenience sake put into the form of duties to some public officer who represents the sovereign.

Other duties are owed to private persons; and if these are violated the sanction is inflicted in such person's name and only at his request. The sovereign indeed furnishes the means of redress, such as courts and officers, but does not spontaneously take any steps in the matter. It seems to be a mere question of words, whether we say that these last named duties are owed to private persons only, or that all duties are owed to the sovereign, some to him alone and others also to private persons.

How it is known who the person is to whom any particular duty is owed cannot conveniently be here explained, but will be shown further on.1

§ 110. The Elements of a Legal Duty. A legal duty implies the following elements: (1) A person on whom the duty rests, who is called the person of inherence of the duty, (2) A person to 1 See & 124.

whom it is owed, who may be designated as the person of incidence,1 and (3) Certain acts or omissions, constituting the content of the duty.

The content of a duty may consist of acts or omissions or both. But omissions, being purely negative, can only be described by describing the acts which are to be omitted. Hence a description of a legal duty must be for the most part a description of the acts commanded or forbidden. A rule of law must contain such a description, together with a command to do or omit the acts described. But acts in the strict legal sense are never as such described in rules of law nor commanded or forbidden. Acts in and by themselves are indifferent in their legal character. All the acts, for example, which are done by a man in murdering another by shooting him with a pistol, the motions of his arm and hand by which the pistol is aimed and discharged, would be perfectly lawful if the actor had no pistol in his hand, or if no one stood in front of it, or even, in some cases, if the pistol were not loaded. Acts are always described for legal purposes by reference to some circumstances additional to and connected with them, whose presence imparts to them their good or bad legal character.

These may be (1) The actual consequences of the act, (2) Its probable consequences at the time of doing or omitting it, or (3) The state of mind of the actor. Hence we have a threefold division of duties; though it must be remarked that the same duty may be defined by reference to more than one set of circumstances, and so fall at the same time under two classes. For example, in burglary the duty broken is a duty not to so act as to cause certain consequences to ensue (the breaking and entering), having at the same time a certain state of mind (the intent to commit a felony).

§111. Classification of Duties by the Definitional Circumstances of the Acts. First, we have what may be called peremptory duties, which are defined by reference to the actual consequences of the act. Here the law sets before a man a certain result and commands or forbids him peremptorily to act so as to bring about that result. The law does not specify the acts. If the result is commanded, the person must do such acts, whatever they are, as may be necessary to attain it; if forbidden, he must abstain from all acts whatsoever which

The expressions person of inherence and person of incidence I have borrowed from Professor Holland, who however, uses them only of rights, not of duties. Holl.

if done would be followed by it. He acts or abstains at his peril. Results so commanded or forbidden we may call the definitional consequences of the act or of the duty. An example of this kind of duty is the obligation to pay a debt. The debtor must do whatever acts are necessary to accomplish the payment, or at least a tender. If he does not do so, he is guilty of a wrong; and the law will not inquire what his state of mind was nor why he failed, nor allow him to excuse himself, even from the payment of costs, by showing that he was prevented by inevitable accident only and not by any fault of his own from paying. Another duty of this class is not to remove the support from land so as to cause it to cave in.1 Duties of this sort, however, may have exceptions which fall under other classes. Thus persons having charge of the construction of public works may be specially authorized to make excavations which will or may cause adjacent land to cave in, and this authority may be limited by the condition of acting in good faith and with reasonable

care.

Secondly, the law does not generally require a person to act or abstain at his peril; but, though it holds up to him a certain end to be sought, it demands from him only efforts towards that end, not its realization at all events. In such cases the duty is not defined by reference to actual consequences. The law places before the party certain possible consequences of his conduct as its end, and then calls upon him to use reasonable endeavors or due care and diligence for its attainment. If he does this, he has performed his duty, though his endeavors prove unsuccessful and the end sought is not in fact attained. These duties may be appropriately named duties of choice, and the end thus set before the party the definitional end of the duty. Most duties as to intention, negligence, malice and fraud, as those words are commonly used in our law, fall into this class. The duty of a partner, for instance, is also commonly to use due diligence to promote the interests of the firm, but he is not peremptorily bound to insure its prosperity.

Thirdly, some duties are defined by reference to the state of mind of the party which accompanies or prompts to the act. Such is the duty in § 469, not to do any act with the intention of thereby causing pecuniary loss to another; and duties whose breach involves

1 See 421; Humphries v. Brogden, 12 Q. B. N. S. 739; S. C., 20 L. J. Q. B. 10; Gilmore v. Driscoll, 122 Mass. 199.

2 Ch. VIII, IX.

actual intention, or malice generally. These may be designated as duties of intent, although they perhaps include, or might conceivably include, a few duties where intention is not an element in the definitional state of mind.

§ 112. Duties as to Events. There are two apparent exceptions to the principle that the content of a duty consists, positively or negatively, of acts. One occurs where a retrospective law apparently creates a duty in the past. This has been already explained.' The other is where a person binds himself by contract for the act of another or even for the mere happening of an event or the existence of a state of facts, as in the covenants for quiet enjoyment or against incumbrances in deeds of real property. But these too are only apparent exceptions, the contract being in substance one of indemnity and thus concerned with the future conduct of the parties, i. e., the payment of money.2

II-CORRESPONDENT RIGHTS.

§ 113. The Nature of Correspondent Rights. The word right is used in law in four different senses, which it will be necessary to describe separately. In all of these senses, with the doubtful exception of the last, rights may be said to in some way correspond to duties; the word right always connotes the idea of duty. But the species of rights that I intend to describe first correspond so much more directly and specifically to particular duties that they may appropriately be distinguished from the others by the name of correspondent rights.

The person to whom a duty is owed has a right to have the acts which compose the content of the duty done or omitted. A right of this kind is the condition of having a duty owed to one's self. Such a right may be analyzed in the same manner as a duty. The person having the right, who is of course the person of incidence of the duty, is the person of inherence of the right; the person against whom the right exists, the person of inherence, that is, of the corresponding duty, becomes the person of incidence of the right; and the content of the right is the same as that of the duty. This agrees with Austin's description of a right, except that he uses the word object to denote the act or omission which I have called 2 Richard v. Bent, 59 Ill. 38; S. C., 14 Am. Rep. 1.

1 See ? 16.