When this case was here before, 260 Mass. 110, it was settled that the issues of the due care of the plaintiff’s intestate and the negligence of the servant of the defendant were questions of fact for the jury. In legal aspects material to those issues, the evidence on the present record is not essentially different from that at the former trial. It would be futile to review the evidence or repeat the discussion. Those issues are foreclosed in favor of the plaintiff.
The defendant has argued that the evidence is not sufficient to warrant a finding of actively intelligent and energetic attention to safety required in cases of this nature, relying *458in this connection upon Hudson v. Lynn & Boston Railroad, 185 Mass. 510, 521, and Bothwell v. Boston Elevated Railway, 215 Mass. 467, 470. That contention cannot be supported. It is not relevant to the facts of the case at bar. The presumption of due care created by G. L. c. 231, § 85, in any event is coextensive with the requirement as to due care expounded in the Hudson case. That presumption was not inapplicable as matter of law to the case at bar. Mercier v. Union Street Railway, 230 Mass. 397, 403, 404. The case on this point is covered by the authority of King v. Weitzman, 267 Mass. 447, 450.
There was no error in the charge to the effect that the burden of proof of showing want of due care of the decedent was on the defendant. By G. L. c. 231, § 85, in all actions “to recover damages for injuries to the person or property or for causing the death of a person, the person injured or killed shall be presumed to have been in the exercise of due care, and contributory negligence on his part shall be an affirmative defence to be set up in the answer and proved by the defendant.” Contributory negligence on the part of a person injured or killed through the negligence of another is want of due care in respect to the cause of the injury or death and is itself conduct haying a share in bringing on the harm. Want of due care by the person injured, touching the cause of his injury resulting from the negligence of another, is contributory negligence. Due care" and contributory negligence on the part of a person injured or killed through the negligence of another are correlative terms; one states his essential positive duty with reference to his own safety and the other his failure in performance of that duty; both imply conduct touching the proximate cause of his injury. They relate to the causal connection between his conduct and his injury, with respect to the tortious conduct of the defendant. Due care in this connection means that care for his own safety required by the law. Contributory negligence means violation of the duty to care for one’s own safety which exists at least in those cases where a person who has sustained an injury seeks to fasten liability for that injury upon some other person. The statement, from Bergeron v. Forest, 233 *459Mass. 392, at page 399, viz.: “Negligence consists in doing or omitting to do an act in violation of a legal duty or obligation due to the person sustaining injury” upon which the defendant relies as drawing a distinction between due care and contributory negligence does not support that distinction. That statement is equally descriptive of the contributory negligence of the plaintiff and of the positive negligence of a defendant. The conventional definition of due care as the kind and degree of care that persons of ordinary prudence would exercise in the same circumstances of place, time, and attendant conditions in its practical application to the trial of cases is not an abstraction. It is practical, specific, definite. It is descriptive of conduct with reference to the cause of action on trial, not with reference to unrelated matters. It is conceivable that a plaintiff in an action for negligence might be wanting in due care with respect to an indifferent matter and yet be in the exercise of due care with respect to the cause of the injury inflicted on him through the negligence of the defendant. Negligence which does not contribute to the injury is immaterial and irrelevant. Marble v. Ross, 124 Mass. 44, 48. The contention of the defendant as stated in his brief is that contributory negligence “implies some act of the plaintiff in violation of some duty of plaintiff to defendant, which act cooperating with the defendant’s negligence, or violation of his duty to the plaintiff, contributed to the accident.” Possibly that contention interpreted in a highly technical sense may mean that violation of a duty owed by the plaintiff to the defendant, not actually causing or likely to cause injury to the defendant exercising due care, nevertheless is wanting in due care to the extent of having a causal connection with the injury to the plaintiff arising from negligent conduct of the defendant. If it means that, there are two fatal objections to it: (1) it is too refined to be of any practical value; (2) it is not sound in law because contributory negligence in the sense used in said § 85 refers to conduct of the plaintiff with reference to his own injury and not with reference to a duty owed by him to the defendant. The quoted contention of the defendant interpreted in its natural signification means that the violation by the *460plaintiff of some duty to the defendant must be of such nature as might be the foundation of an action sounding in negligence by the defendant against the plaintiff. In that sense it does not correctly state the law. The “contributory negligence” of the plaintiff as used in said § 85 does not necessarily refer to an act constituting a definite wrong against the defendant which might of itself constitute a cause of action by the defendant against the plaintiff. It may comprehend such an act. But the essential factor in contributory negligence under said § 85 is an act wanting in due care which of itself has a causal connection with the injury suffered by the plaintiff, wholly regardless of the point whether it was an independent wrong against the defendant. The failure of a plaintiff to. exercise due care was described as negligence by Shaw, C.J., in May v. Princeton, 11 Met. 442, 444. It was said in Railroad Co. v. Gladmon, 15 Wall. 401,406: “While it is true that the absence of. reasonable care and caution, on the part of one seeking to recover for an injury . . . will prevent a recovery, it is not correct to say that it is incumbent upon him to prove such care and caution. The want of such care or contributory negligence, as it is termed, is a defence to be proved by the other side.” The instances are not infrequent where “want of due care” has been used to describe negligence. That description often has been deemed sufficient for the purposes of a particular decision. Sweeny v. Old Colony & Newport Railroad, 10 Allen, 368. Minor v. Sharon, 112 Mass. 477, 487. Jager v. Adams, 123 Mass. 26, 27. Railroad Co. v. Jones, 95 U. S. 439, 441, 442. Of course it is not a complete and accurate definition of negligence to say that it is conduct wanting in due care. To make that definition other elements must be stated, as violation of duty and causal connection with injury. Bernabeo v. Kaulback, 226 Mass. 128. Mammott v. Worcester Consolidated Street Railway, 228 Mass. 282, 284. Altman v. Aronson, 231 Mass. 588, 591. Pickett v. Waldorf System, Inc. 241 Mass. 569, 571. Northern Pacific Railway v. Adams, 192 U. S. 440, 449, 450. But it is not necessary in judicial opinions or in statutory enactments to define completely every term used.
It follows that in the case at bar as a practical guide to a. *461jury or other fact finding tribunal, as the words are used in said § 85 there is no distinction between "due care” describing the presumption as to the conduct of the plaintiff and "contributory negligence” describing the burden of proof resting upon the defendant. Powers v. Loring, 231 Mass. 458, 460, 461. The trial judge rightly made no attempt to draw any distinction between the two in stating that the burden of proof in that particular rested upon the defendant.
There was no error in the reference in the charge to the circumstance among others that the horse of the defendant was left standing unhitched at a time when the pangs of hunger might be operative. That was a factor needing no express proof beyond the time of its last feeding. It might be thought by the jury as entitled to weight. Turner v. Page, 186 Mass. 600. Hayes v. Wilkins, 194 Mass. 223. Johnstone v. Tuttle, 196 Mass. 112.
There was no error in the refusal to give the requests of the defendant. Whether it was negligence to leave the horse unhitched and unattended at a street curb, near the end of his work for the day, in a place of much traffic was in all the circumstances a question of fact. All the contentions argued by the defendant have been considered and no error is disclosed.
Exceptions overruled.