— Plaintiff brought this action to recover certain instalments of rent, due from defendant according to the covenants of a lease dated April 24, 1884, under the seals of both parties, whereby plaintiff let certain business property in Kansas City, Missouri, to defendant for one year from May 1, 1884, on terms, one of which was the payment of $1,000 rent during that period. Defendant went into possession and concedes non-payment of the rent in dispute. The reason therefor appears in the counterclaim interposed. That part of defendant’s answer and the evidence supporting it raise the only question presented on this appeal.
*197Defendant’s position is that the rent due is subject to reduction to the extent of damages sustained by defendant by the breach of a verbal agreement between plaintiff and defendant, the admissibility of which in evidence is the point in dispute.
The trial court heard defendant’s testimony on the subject fully (over objections), and then directed a verdict for plaintiff, a stipulation having been made at the outset of the trial, that plaintiff was entitled to recover the amount claimed unless the defense in question was established.
The facts shown on defendant’s part were that it was engaged in the manufacture and sale of cornshellers and other farm machinery at Decatur, Illinois. It rented the premises at Kansas City as a storehouse and business office. When the negotiations for the lease began, it was verbally agreed, between plaintiff and defendant’s representative, that the former would put in a railway switch (to connect the premises with a railroad near by) for the use of defendant for shipping purposes. Something was then said about inserting this stipulation in the lease, but plaintiff declared it was not necessary as the thing would be done by the time defendant would be ready to use the track after moving in, adding that his word was as good as his bond. Shortly afterwards the lease was prepared in Kansas City, and forwarded to Decatur for signature on the part of defendant. On examining its terms, the defendant made an amendment by inserting the words, “ also office desk room and space for sample machine on first floor” (as they now appear). Then the instrument was formally executed by both parties. It contains no such express agreement as defendant now insists upon, concerning a railway switch.
It will be assumed that defendant’s proof showed substantial damages in consequence of the want of the railway connection mentioned.
*198On this showing the trial court directed a verdict for plaintiff. In due course defendant appealed to the Kansas City court of appeals where the judgment was affirmed. The cause, however, was certified to the supreme court as directed by the constitution, in view of a division of opinion among the judges of the court of appeals. Tracy v. Iron Works (1888), 29 Mo. App. 342.
It should be noted that the verbal agreement asserted by defendant was made in the preliminary negotiations leading to the written lease, and that the latter purports to be complete in itself. It defines with particularity the property whose use was let to defendant. Part of it consisted of privileges in the nature of easements (for example, the use of the elevator and platform in common with other tenants ), appurtenant to that part of the property of which defendant was to enjoy exclusive occupancy. The principal subject-matter of the letting was the upper story of the building, numbered 1305, 1307 and 1309, West Twelfth street, in Kansas City, Missouri, “in the present condition thereof.” The terms, reserving rent, are clearly expressed and many customary stipulations in regard to repairs, underletting and care of the premises, appear.
' Defendant contends that plaintiff’s prior agreement to add a railroad switch to the demised premises should be regarded as collateral to the lease, and admissible as such. It is not denied that verbal evidence in contradiction of written, and especially of sealed, documents is usually inadmissible; but the case here is said to belong to a recognized class of exceptions to that rule. Waiving all question that might arise from the form of the lease as a specialty and treating it merely as a written contract, let us examine the merits of defendant’s contention.
The general rule excluding evidence of contemporaneous, or prior verbal agreements, varying or *199contradicting the terms of a valid written instrument, is the outgrowth of the common experience ofmen. It is of great antiquity and appears in other systems of jurisprudence besides our own. Corp. Jur. Civ., Cod. Lib. 4, Tit. 20; Tait’s Evid., pp. 326, 327.
It rests on principles somewhat analogous to those which underlie the doctrine of the conclusiveness of judgments upon parties thereto. It is said to be the interest of the state that there should be an end to litigation. Accordingly, the record that closes a forensic controversy is regarded as merging the matters litigated to the extent declared in the judgment. So, in private adjustments of reciprocal rights, it is wisely considered that, when parties have deliberately put their mutual agreements into the form of a completed written contract, that expression of their intention should be accepted as a finality, in which is merged all prior negotiations within the scope of the writing.
But the rule has too long occupied a place as a corner-stone in the law of evidence to require, at this day, any justification of its existence.
We may, however, properly remark that the adoption of the modern practice, admitting as witnesses the parties directly interested in the action, seems to add a cogent reason to those existing at the common law, for a close adherence to the rule under discussion. If the uncertainty of “slippery memory” furnished a ground for excluding such verbal testimony in the days of Lord Coke (Countess of Rutland v. Earl of Rutland (1604), Coke’s Reports, Part 5, 26a), how much stronger reason for such exclusion to-day when the influence "of self-interest is so likely to render the memory of litigating parties more “slippery” than was that of the witnesses of olden time.
In Missouri the general rule has been repeatedly approved in early, as well as recent, decisions. Woodward v. McGaugh (1843), 8 Mo. 161; Walker v. Engler (1860), 30 Mo. 130; State ex rel. v. Hoshaw (1889), 98 *200Mo. 358; Morgan v. Porter (1891), 103 Mo. 135; 15 S. W. Rep. 289.
There are, however, cases, here and elsewhere, announcing propositions called exceptions to this rule. Some may fairly be so described, as, for example, those admitting parol evidence to contradict a recited consideration, or to show that, in equity, an absolute deed was intended as a mortgage. But it will be found, we think, that many rulings, on this topic, which, at first sight, appear exceptional, are rather instances not embraced within the true meaning and scope of the rule. As such may be mentioned cases in which fraud, mistake or illegality has prevented the written instrument from acquiring original vitality as a contract, or those admitting evidence to identify its subject-matter, as well as others in which the writing, on its face, appears to be an incomplete, or merely one-sided expression of the terms of agreement. Rollins v. Claybrook (1856), 22 Mo. 405; Moss v. Green (1867), 41 Mo. 389.
The pending appeal does not demand any attempt to classify the so-called exceptional cases., Especially do we abstain from any effort to indicate what kind of verbal agreements may be shown, collateral to a written one, beyond the requirements of the appeal now actually in hand.
The facts in the present record disclose that the verbal agreement, proposed to be shown, contemplated a substantial addition by the plaintiff to the property which was the subject of the demise, whereas the terms of the written 'lease between the parties declared that the premises were let “in the present condition thereof.”
Obviously the oral testimony in question contradicted the very language of the writing in which these business men, dealing at arm’s length, had deliberately expressed themselves. We think the learned circuit judge correctly held such testimony inadmissible and that it could find no proper place in the case made by the pleadings, without departing from sound principle *201and precedents. Brigham v. Rogers (1822), 17 Mass. 571; Cleves v. Willoughby (1845), 7 Hill (N. Y.). 83 ; Howard v. Thomas (1861), 12 Ohio St. 201; Naumberg v. Young (1882), 44 N. J. L. 331; Diven v. Johnson (1888), 117 Ind. 512; Stoddard v. Nelson (1889), 17 Oregon, 417; McLean v. Nichol (1890), 43 Minn. 169 ; Gordon v. Niemann (1890), 23 N. E. Rep. (N. Y.) 454.
We do not deem it necessary to review all the decisions pointing to this, conclusion. On the other hand the precedents cited by defendant, as illustrative of collateral verbal agreements that have been upheld, we apprehend are inapplicable to the facts of the case now in judgment.
The decision in Brown v. Bowen (1886), 90 Mo. 184 (in view of which this cause was' certified here), is not to be considered, and was not intended to conflict with any of the rulings announced herein.
We regard the action of the trial court as correct and accordingly affirm the judgment of the Kansas City court of appeals, which was to the same effect.
ShebwooDj C. J., Black and Bbace, JJ., concur. ’