WALKER, J.
When the appellee received the injury which is the occasion of this suit he was employed as a track-hand at the mines of the appellants. The entries from which the ore was mined were on the side of a mountain. An inclined railroad was used in carrying the ore from the entries down the mountain side. There were two parallel *313tracks. Tlie dumps or cages on which the ore was carried ran on one of them. A dummy or weight ran on the other track. The cage and the dummy were connected by a wire rope which passed over a pulley or wheel situated above the tracks on the mountain side. "When the cage was loaded it was heavier than the dummy, and its weight carried it to the bottom. When the cage was unloaded, it was pulled up to the mines by the heavier dummy running down the other track. As the cage went down, the dummy was pulled up; and as the cage ascended, the dummy at the other end of the rope descended. There were brakes on the cage, and also at the pulley or wheel. The wire rope which connected the cage and the dummy ran on top of the ground, over rollers which were fastened to the cross-ties, so that a person on either track could tell by the presence or absence of the rope whether the vehicle which ran on that track was then below or above. The testimony of the plaintiff himself tended to show that the boss of the mine ordered him to go from one of the entries where he was working, to bring some spikes, which he says were on the cage track lower down, telling him in substance that the cage was not above, but was at the bottom of the incline; that he went down the cage track, and while stooping down on the track picking up the spikes, the cage was run down the track from above, and struck him. The evidence for the defendants tended to show that the plaintiff was struck while attempting to walk from one side of the track to the other, in front of the descending-cage, which was in full view. The plaintiff’s version of the occurrence was not supported by the testimony of any other witness.
The suit is prosecuted by a next friend in behalf of the plaintiff, the complaint alleging that the plaintiff himself is a person of unsound mind, and that he has no guardian appointed in this State. — Code, § 2580. So long as the suit is prosecuted in this mode, the plaintiff can not be heard to deny that he is of unsound mind, as alleged in his complaint. He stands before the court in the attitude of admitting his mental incompetency. It does not, however, follow from the fact that a person is incapable of managing his own affairs, or of having charge of litigation in which his interests are concerned, that he is incompetent to testify as a witness. There are many grades and phases of mental unsoundness. One’s infirmity may be such as to render it expedient to place him under guardianship, and even to subject him to personal restraints, and yet he may be fully competent to understand the nature of an. *314oath, to observe facts correctly, and to relate tliem intelligently and truly. A sweeping rule of disqualification which would exclude such a person as a witness would be arbitrary and unsupported by sound reason. The true reason for not admitting the testimony of a person non compos mentis in any case is because his malady involves such a want or impairment of faculty that events are not correctly impressed on his mind, or are not retained in his memory, or that he does not understand his responsibility as a witness. When the reason for the exclusion of the witness does not exist, he should be permitted to testify. The following quotations express what we regard as correct views on this subject: “It will be seen then, that a witness is not excluded by this rule, merely because he is a lunatic. That is not enough per se to exclude him; but he must at the time of his examination be so under the influence of his malady as to be dejn'ived of that ‘share of understanding’ which is necessary to enable him to retain in memory the events of which he has been witness, and give him a knowledge of right and wrong. If at the time of his examination he has this share of understanding, he is competent. That is the test of competency, and of such competency the court is the judge; whilst the weight of the testimony — the credit to be attached to it — is left to the jury. — Coleman’s case, 25 Grattan, 875. “The general rule, therefore, is that a lunatic or a person affected with insanity, is admissible as a witness if he have sufficient understanding to apprehend the obligation of an oath, and to be capable of giving a correct account of the matters which he has seen or heard in reference to the questions at issue; and whether he have that understanding is a question to be determined by the court, upon examination of the party himself, and any competent witnesses who can speak to the nature and extent of his insanity.” — District of Columbia v. Arms, 107 U. S. 521. Other authorities fully sustain the jmopositions, that the question of the competency of a witness because of mental infirmity is one for the court, and that it is for the jury to determine the effect of his. unsoundness of mind upon the credibility' of his testimony. Holcomb v. Holcomb, 28 Conn. 177; Kendall v. May, 10 Allen, 59; Hartford v. Palmer, 10 Johnson, 143; Cannady v. Lynch, 27 Minn. 435; Wharton on Evidence, (2d Ed.) §§ 402, 409; 11 Am. & Eng. Encyc. of Law, 144.
In the present case, it is not made to appear that the plaintiff was so deficient as to require his exclusion as a witness under the rules above stated. It can not, therefore, be affirmed that the court erred in permitting him to testify *315But lie stood before tbe jury confessedly a person of unsound mind. It was for them to determine, from bis appearance and manner, and from tbe other evidence on tbe subject, whether he was so mentally incapable as to render bis testimony unworthy of acceptance. As bis testimony furnished tbe only proof of negligence on tbe part of defendants, charge 10 requested by tbe defendants should have been' given.
Any objection by tbe defendants to tbe interposition of tbe next friend for tbe plaintiff should have been raised before tbe trial upon tbe merits it was entered upon. A charge upon tbe evidence is not a proper mode of raising such an objection.
()n tbe question of tbe plaintiff’s contributory negligence as affected by his mental condition, it is sufficient, for tbe purposes of another trial, to state rules which should guide in tbe consideration of this subject. The plaintiff is to beheld to tbe exercise of tbe degree of care of which be was capable. If be was merely a person of dull mind, who could labor for bis own livelihood, and there was no apparent necessity of putting him under tbe protection of a guardian to keep him out of harm’s way, be is chargeable with tbe same degree of care for- bis personal safety as one of brighter intellect, as any attempt to frame and adapt varying rules of responsibility to varying degrees of intelligence would necessarily involve confusion and uncertainty in tbe law. If, on tbe other band, be was so absolutely devoid of intelligence as to be unable to apprehend apparent danger, and to avoid exposure to it, be can not be said to have been guilty of negligence, because be was incapable of exercising care. When tbe mere negligence of another causes or contributes to tbe injury of a person who is mentally incompetent to such a degree, if tbe conduct of tbe injured person would have avoided bis claim to relief if be bad been capable of exercising care in bis own behalf, ,the person inflicting tbe injury is .not to be held to a liability which would not have been incurred under tbe same circumstances in favor of a jjerson of ordinary capacity, unless be bad notice of tbe injured person’s mental deficiency, and of bis consequent helplessness and peril in tbe circumstances in which be was placed. Tbe duty of observing special precautions for tbe safety of another, because tbe latter, by reason of mental imbecility, can not be influenced by tbe dictates of ordinary prudence, is not cast upon one who is not charged with notice of tbe other’s peril and of bis lack of sufficient intelligence to avoid it. "When it is sought, in behalf of an *316adult, to avoid the consequences of bis own conduct, and to charge another with liability for a result to which such conduct contributed, the burden is upon him to show that he was not responsible for his own acts, and that the person sought to be charged was under the duty of dealing with him as one incompetent to care for himself. The mental deficiency of an adult which would exempt him from accountability for his own conduct proximately contributing to his personal injury, would also render him an incompetent witness of the occurrence in which the injury was received.
Beversed and remanded.