ON MOTION FOR REHEARING
PER CURIAM:In his motion for rehearing defendant insists that we have misinterpreted the law in holding that his Instruction 7 did not controvert an essential factual element of plaintiff’s case. He calls attention to the conflict in the evidence touching the manner in which the accident occurred, cites plaintiff’s testimony to the effect that “ * * her car stopped behind the car ahead in the northbound lane and * * * did not strike the car ahead before it was hit by the defendant,” and declares that “[t]hat was her theory of the case.” He then concludes that Instruction 7 was a proper converse of those allegedly essential factual elements of her case because it “ * * * required the jury to find that the plaintiff’s automobile slowed suddenly and skidded and collided with the car ahead before the collision with defendant’s automobile (rather than coming to a stop or almost to a stop) and that the collision occurred on the east shoulder (not on the highway).” Cited in support of that proposition are Frechin v. Thornton, Mo., 326 S.W.2d 122, McCarty v. Milgram Food Stores, Inc., Mo., 252 S.W.2d 343, and Rollins v. Postlewait, Mo., 358 S.W.2d 828. A review of those cases, and others cited therein, will be helpful in considering and disposing of defendant’s point.
In Frechin v. Thornton, supra, plaintiff’s evidence was to the effect that she was attempting to pass defendant’s truck on its left when, without warning, the truck swerved sharply to the left across the center line of the highway in the course of making a left turn onto a side road, crowding her car off the highway into a ditch. Defendant denied it. Plaintiff’s verdict-directing instruction submitted that “ * * * defendant turned to the left across the center line of said highway and upon the east shoulder of the highway in front of the automobile in which plaintiff was riding * * Defendant countered with an instruction authorizing a verdict in his favor if the jury found that at all times in question he operated his truck “ * * * upon the right half (west) of the paved portion of U. S. Highway No. 71 by-pass, and did not operate said truck to the left (east) of the center line of said highway * * It was held that defendant’s instruction was a proper converse of an essential factual element of plaintiff’s case. And obviously it was.
In McCarty v. Milgram Food Stores, Inc., supra, plaintiff was injured when a Coca *614Cola sign fell on her while she was shopping in defendant’s store. She submitted her case under the res ipsa loquitur doctrine. In a res ipsa case, of course, the defendant’s control of the instrumentality causing the injury is an indispensable prerequisite to plaintiff’s recovery. She therefore required the jury to find that the sign “ * * * was in the exclusive possession and control of the defendant * * And defendant’s counter-instruction told the jury that no verdict could be returned in plaintiff’s favor unless she had established “ * * * tliat the Coca Cola sign mentioned in evidence was in the exclusive possession and control of the defendant * It was held that defendant’s instruction was a proper converse of an essential factual element of plaintiff’s case. And obviously it was.
In Conser v. Atchison T. & S. F. Ry. Co., Mo., 266 S.W.2d 587, plaintiff claimed to have been injured by the “unusual and extraordinary” jerk of the freight train on which he was riding. His main instruction required the jury to find that the “ * * ‘jerk of said caboose was unusual and extraordinary.’ * * * ” Defendant’s counter-instruction advised the jury that even though the train j erked, still if “ * * * the force of the jerk was not unusual and extraordinary in the operation of freight trains * * * ” plaintiff could not recover. It was held that defendant’s instruction was a proper converse of an essential factual element of plaintiff’s case. And obviously it was.
In Schaefer v. Accardi, Mo., 315 S.W.2d 230, the court observed that in a personal injury case the injury itself was a vital element of the claim. Indeed, it is the very bone and marrow of such a case; and plaintiff’s instruction accordingly required a finding in his favor on that issue. Defendant submitted simply that if “ * * * the plaintiff was not injured on the occasion in question the plaintiff cannot recover * It was held that defendant’s instruction was a proper converse of an essential factual element of plaintiff’s case. And obviously it was.
That brings us to Rollins v. Postlewait, supra, the most recent of the cases examined. In that case plaintiffs brought an action for the wrongful death of their infant son who was killed when defendant backed a truck over him. Plaintiffs’ evidence tended to establish, and their main instruction hypothesized, that the child “ * * * was sitting on the east curb * * * of * * * Forest Avenue * * * ” at the time defendant backed the truck over him. Defendant’s evidence tended to establish that the child was not sitting on the curb but was standing by it when the truck backed over him. Based on that variance in the two versions of the incident, defendant submitted this instruction: “The court instructs the jury that if you find and believe from the evidence that the deceased infant was not sitting on the east curb of Forest Avenue at the time defendant backed his truck upon and over him, then your verdict must be for the defendant Mr. Postlewait, regardless of any other fact or circumstance shown in evidence.” It was held that defendant’s instruction was a proper converse of an essential factual element of plaintiff’s case
The only authority cited in support of that conclusion is the Schaefer Case, reviewed next above. The casual reader, however, may find the similarity between those two cases somewhat more elusive than the citation of one in support of the other would ordinarily imply. The “essen-tiality” of the child’s exact position behind the truck at the time it crushed him does not appear to have been determined by quite so familiar a standard as that which leads to the conclusion, for instance, that an injury of some kind is essential to a plaintiff’s recovery in a personal injury action. In consequence, we find defendant in this case insisting that the factual issues as to whether plaintiff struck the car ahead of her before or after she was hit from behind by defendant’s car, and as to whether her car *615was on or partially off the paved slab at the time she was hit, were just as essential in this case as was the position of the child in the Rollins Case.
While not denying the persuasiveness of the analogy, we think the decision in this case need not be dictated by it. We do not believe the court intended to leave the impression that the question of essentiality in the Rollins Case was being determined by the identical standard applicable to the Schaefer Case. An analysis of all the cases reveals that the question of essentiality of the controverted issue has invariably arisen, not upon a mere conflict in the evidence as to the existence of a particular fact, but upon plaintiff’s submission of that fact in his main instruction as one required to be found as a prerequisite to his recovery. That circumstance is not without significance. It suggests a principle by which all the cases in which the question has arisen, or is likely to arise, may be reconciled. These fall logically into three classes, to be examined in their order.
In the first class the fact in dispute will be found to have been so essential to plaintiff’s recovery that under our rules of practice he was required to hypothesize it in his verdict-directing instruction. In such cases the defendant’s instruction submitting the converse of the dispute is obviously proper and we have no problem. Typical of these is the Schaefer Case.
In the second class the fact in dispute will be found to be, or at any rate should be, one of evidentiary significance although not absolutely essential to plaintiff’s recovery. In such a case the plaintiff is not required to hypothesize it in his main instruction but, for reasons that recommend themselves to him as tactically advantageous, he may elect to do so. If he so elects, and stakes his recovery on the jury’s finding the fact in his favor, the defendant may submit the converse of it as authorizing a verdict for himself, and the plaintiff will not afterwards be allowed to deny that it possessed the quality of essentiality with which he himself invested it. He is sometimes said to be estopped to do so; but as suggested in Lindquist v. Kansas City Public Service Co., 350 Mo. 905, 169 S.W.2d 366, where an analogous proposition was under discussion, it is more precise to say that he will not be heard to complain of an error which he has himself invited. We think the Rollins Case was intended to be based on that principle. The clue is found in this sentence, 358 S.W.2d l. c. 831: “Plaintiffs chose by instruction 1 to require the jury to find as prerequisite to a plaintiffs’ verdict that while Ricky was sitting on the east curb of Forest the defendant backed his truck upon and over him.”
In the third class of cases, of which this one is the example in point, it will be found that the fact in dispute has never risen to the dignity of a factual issue or essential factual element of plaintiff’s case for the reason that, being neither required by law to hypothesize it nor having elected to do so, plaintiff refrained from submitting it to the jury for determination in her favor as a prerequisite to a verdict for her. Her main instruction reads as follows: “The court instructs the jury that if you find from the evidence on the occasion mentioned in evidence that plaintiff was riding as a passenger in an automobile being operated north-wardly on Highway 61 in a line of traffic, if you so find; and if you further find that at about the same time the defendant Hubert Sitz drove and operated his automobile in a northwardly direction on Highway 61 at about sixty feet to the rear of the automobile in which plaintiff was riding and at a speed of about thirty-five to forty miles per hour, if you so find; and if you further find that thereafter under the aforesaid conditions the automobile in which plaintiff was riding slowed down until it was stopped or almost stopped, and that thereafter the automobile of the defendant collided with the rear end of said automobile and the plaintiff was injured as a direct result of said collision, if you so find; and if you further find that prior to the time that the automo*616bile in which plaintiff was riding started to -slow that the operation by the defendant of liis automobile at a speed of thirty-five to forty miles per hour about sixty feet behind the car in which plaintiff was a passenger was too close and was dangerous and not reasonably safe and a collision was likely to occur should the car in which ■plaintiff was a passenger slow and stop, if .you so find; and if you further find from the evidence that the defendant knew or by the exercise of the highest degree of care should have known that operating his vehicle in said manner was too close and was dangerous and not reasonably safe should the car in which plaintiff was a passenger slow and stop, if you so find; and if you further find that in so operating his vehicle he failed to exercise the highest degree of care and was thereby negligent, if you so find; and if you further find that said negligence directly caused or contributed to cause the collision and injury to plaintiff, then your verdict shall be in favor of the plaintiff and against the defendant.”
The instruction does not require the jury to find whether plaintiff struck the car ahead of her before or after she was hit from behind by defendant’s car (or at all, for that matter), nor does it require a finding as to whether plaintiff’s car was on or partially off the paved slab at the time she was hit. The conflicting evidence as to those details found no place in her instruction. A determination of the dispute over them was not essential to her recovery as a •matter of law, nor did she elect to make it so by requiring the jury to resolve it in her favor. Hence, she cannot be said either to have invited the defendant to hypothesize those details and predicate a verdict in his favor on the jury’s finding he was right about them, or to have estopped herself to complain of the error when he did. Even if the disputed facts had been hypothesized in plaintiff’s instruction we would reserve the right to decide whether they had any real evidentiary significance. Since they were not, no decision is necessary. It may not be amiss to add, however, that in framing the principle by which we hope our decision in this case has been reconciled with that in the Rollins Case, and the two of them with all the other decisions on the subject, we advisedly used the term “eviden-tiary significance” as descriptive of the type of disputed fact which a plaintiff might, by election to hypothesize it in his main instruction, transmute into an essential factual element of his case, it being our purpose to select a term readily distinguishable from the word “essential” in its usual sense, while at the same time laying to rest any notion that a plaintiff’s hypothesis of an accident occurring on Tuesday would warrant the defendant’s submission of an instruction exculpating him if the jury should find that the accident occurred, say, on Wednesday.
We adhere to our original ruling that defendant’s Instruction 7 did not constitute a proper converse of any essential factual element of plaintiff’s case, and that it was vulnerable to the criticism leveled against it. The motion for rehearing is denied.