after stating the case: Plaintiffs were nonsuited and barred from participation in the proceedings ostensibly upon the ground that no showing of demand upon the executor to bring the action and refusal on his part had been made at the time the evidence of mental incapacity was offered. Plaintiffs had, however, previously challenged the right of the executor to act in the premises by filing caveat to the will, and it appears that the executor has joined with his wife and •codefendant in the present action in supporting her claim and denying the allegations of the complaint. The executor is clearly in opposition to the plaintiffs. This was sufficient under the principle that the law will not require a vain or useless thing to be done. Shuford v. Cook, 164 N. C., 46, 80 S. E., 61; McGuire v. Williams, 123 N. C., 349, 31 S. E., 627; Woolen Co. v. McKinnon, 114 N. C., 661, 19 S. E., 761; Nixon v. Long, 33 N. C., 428.

The matters pleaded in defense, upon proper showing, may be amply sufficient to defeat the plaintiffs’ claim. This, however, would not seem to justify the exclusion of their evidence or the judgment of nonsuit. The competency of the evidence is not seriously questioned. It is well ■established that anyone who has observed another, or conversed with him, or had dealings with him, and a reasonable opportunity, based thereon, of forming an opinion, satisfactory to himself, as to the mental •condition of such person, is permitted to give his opinion in evidence upon the issue of mental capacity, although the witness be not a psychiatrist or expert in mental disorders. S. v. Keaton, 205 N. C., 607, 172 S. E., 179; White v. Hines, 182 N. C., 275, 109 S. E., 31. “One not an expert may give an opinion, founded upon observation, that a certain person is sane or insane.” Whitaker v. Hamilton, 126 N. C., 465, 35 S. E., 815.

Any witness who has had opportunity of knowing and observing the ■character of a person, whose sanity or mental capacity is assailed or *526 brought in question, may not only depose to the facts he knows, but may also give in evidence his opinion or belief as to the sanity or insanity of the person under review, founded upon such knowledge and observation, and it is for the jurors to ascribe to his testimony that weight and credibility which the intelligence of the witness, his means of knowledge and observation, and all the circumstances attending his testimony, may in their judgment deserve. Clary v. Clary, 24 N. C., 78.

After sustaining the demurrer to the evidence, Jensie Aycock was permitted to proceed to try her claim of title to the insurance funds, and the plaintiffs were barred from further participation in the proceedings. At this, counsel for plaintiffs complain, because, they say, they were thereby involuntarily required to play a role somewhat similar to that of Abner Dean in Bret Harte’s “The Society Upon the Stanislaus” :

“Then Abner Dean of Angel’s raised a point of order — when A chunk of old red sandstone took him in the abdomen, And he smiled a kind of sickly smile, and curled up on the floor, And the subsequent proceedings interested him no more.”

If counsel were thus embarrassed, as they doubtless facetiously suggest, it is enough to say a reversal of the judgment of nonsuit ex necessitate vacates all that transpired thereafter which adversely affected their interests. Hargett v. Lee, 206 N. C., 536, 114 S. E., 498. This gives them another opportunity to be heard.

Reversed.