Schenck, J.

We are of the opinion that the merits of this appeal turn upon the question: Does the defense set up in the defendant’s answer constitute a plea in bar of reference of the plaintiff’s first alleged cause of action? If this question be answered in the affirmative, the order of compulsory reference should be reversed; if answered in the negative, such order should be affirmed.

It may be conceded that the mere denial of the relationship of principal and agent between the plaintiff and defendant will not constitute a plea in bar of reference. Reynolds v. Morton, 205 N. C., 491, 171 S. E., 781. However, the defendant goes further than denying this relationship *519 and alleges that even if it be found that such relationship existed the plaintiff well knew of the defendant’s selling other products than those of the plaintiff, and with such knowledge acquiesced and consented to such action on the part of the defendant. If such allegation of the defendant be proven, the acquiescence and consent of the plaintiff to such action of the defendant would constitute a waiver of the plaintiff’s right to complain and completely defeat his first alleged cause of action.

“ 'The strict performance of a contract may be waived. A person for whose benefit anything is to be done, may, if he pleases, dispense with any part of it, or circumstance in the mode of performance. Where he is present to receive performance, whatever is not exacted is considered as waived, for if objection had been made on the ground of those matters in which the proposed performance was deficient, these might have been supplied at the time, and therefore it is not proper to surprise the party who performed the act, by an objection to the mode of performance, after his vigilance has been disarmed by an apparent acquiescence, for that would be a fraud.’ 6 R. C. L., 990; Decamp v. Foy, 9 A. D., 372.” Morrison v. Walker, 179 N. C., 587, 103 S. E., 139.

“The doctrine of waiver, in proper cases, is now as firmly established as the doctrine of the rigidity and inflexibility of the written word. For instance, it is stated in Highway Commission v. Rand, 195 N. C., 799, 141 S. E., 892 : 'Provisions in a contract may be waived.’ A waiver has been variously defined and applied. See Mahuen v. Elder, 170 N. C., 510, 87 S. E., 334; Allen v. Bank, 180 N. C., 608, 105 S. E., 401. An extensive discussion of the principle is found in Mfg. Co. v. Building Co., 177 N. C., 104, 97 S. E., 718. The Court assembles various definitions of the term, including the following from Herman on Estoppel: ‘A waiver takes place where a man dispenses with the performance of something which he has a right to exact. A man may do that not only by saying that he dispenses with it, that he excuses the performance, or he may do it as effectually by conduct which naturally and justly leads the other party to believe that he dispenses with it.’ ” Mfg. Co. v. Lefkowitz, 204 N. C., 449, 168 S. E., 517.

“What constitutes a plea in bar has been considered and accurately defined by this Court in Bank v. Evans, 191 N. C., 538, as follows: 'In a legal sense it is a plea or peremptory exception of a defendant, sufficient to destroy the plaintiff’s action, a special plea constituting a sufficient answer to an action at law, and so called because it barred — i.e., prevented — the plaintiff from further prosecuting it with effect, and, if established by proof, defeated and destroyed the action altogether.’ Haywood County v. Welch, 209 N. C., 583; Jones v. Beaman, 117 N. C., 259.” Preister v. Trust Co., 211 N. C., 51, 188 S. E., 622.

*520 We are constrained to bold that tbe allegation of acquiescence and consent by tbe plaintiff to tbe action of tbe defendant in selling products of others than of tbe plaintiff is an allegation of a waiver of tbe plaintiff’s right to complain of such action of tbe defendant, and that tbe allegation of a waiver of tbe right of tbe plaintiff to complain constitutes a plea in bar of a compulsory reference, since it raises an issue which ought to be settled before such reference is bad. Tbe issue goes to tbe very heart of tbe controversy, and if answered in favor of tbe defendant completely settles tbe whole controversy, without tbe expenses and time incident to a reference. We, therefore, conclude that tbe answer to tbe question posed in tbe outset should be in tbe affirmative, and that it was error to have ordered tbe compulsory reference prior to tbe determination of tbe plea in bar. Cheshire v. First Presbyterian Church, 221 N. C., 205, 19 S. E. (2d), 855; Preister v. Trust Co., supra; Banks v. Evans, 191 N. C., 535, 132 S. E., 563.

The order of compulsory reference entered by the court below is

Reversed.

DeviN and Babkhill, JJ., concur in result.