Both on the basis of the four corners of the contract and the context in which the interrogation proceeded, the trial court properly excluded parol evidence.

Defendant’s counsel, in direct examination of his own witness, asked: “All right now, Mr. Hoffman. During the negotiations that culminated in the execution of this contract between your company and Delta Dynamics, was there any conversation or discussion as to what would happen as far as Pixey Distributing Company is concerned if they, failed to meet the minimum quota set up in that contract?” (Italics added.)

An objection was made by plaintiff’s counsel and sustained by the court. Defense counsel neither made an offer of proof nor any further effort to demonstrate there was an ambiguity in the contract, or if there was, to offer an explanation.

On that frail record of a fleeting and demonstrably improper single question, the majority reverse a judgment to which the trier of fact found plaintiff clearly entitled on the weight of the evidence.

It is hornbook law that conversations, discussions and negotiations culminating in a written instrument are not admissible in evidence. Indeed, since 1872 Civil Code section 1625 (amended in 1905), has provided that the “execution of a contract in writing, whether the law requires it to be written or not, supersedes all the negotiations or stipulations concerning its matter which preceded or accompanied the execution of the instrument. ’ ’ (Italics added.)

Whether or not defendant’s counsel intended to limit his query to negotiations preceding execution of the contract, the unalterable fact is that he did so. He asked no further questions and made no offer of proof. His efforts on this appeal, and those of the majority of this court, to expand his inquiry beyond the subject of negotiations are an attempt to rewrite the record.

The majority hold that an offer of proof was unnecessary because the pretrial conference demonstrated ‘ ‘ counsel expected his witness to answer that the parties intended termination *531 to be an exclusive remedy.” This is pure legal legerdemain, for while the purpose of the pretrial proceeding is to determine the issues to be tried (VanAlstyne & Grossman, California Pretrial and Settlement Supplement (Cont. Ed. Bar 1967) §3.30), it has always been understood that “the parties’ contentions on those issues are generally regarded as merely tentative, nonbinding descriptions of what the parties hope to prove” (id., §10.14). No authority holds or has hinted that a pretrial discussion or order is a substitute for an offer of proof at the trial.

As stated in Ransom v. Ransom (1963) 215 Cal.App.2d 258, 264 [ 30 Cal.Rptr. 53 ] : “It is a recognized rule that: ‘Ordinarily when the ruling of the court sustaining an objection indicates that counsel may not make further inquiry of a similar nature, he must then make an offer of proof. For example, if an objection is sustained to a question which on its face does not indicate its materiality, counsel asking the question must show the materiality of the question and the expected answer. If counsel fails to make the required offer of proof, he is precluded from urging the exclusionary ruling as error on appeal. [Citation.] The requirement of the offer of proof serves two practical purposes. First, it permits the trial court to reconsider and correct an erroneous exclusionary ruling in the light of all the facts. Second, it permits the appellate court to determine if the ruling was erroneous and, if so, whether it was sufficiently prejudicial to justify a reversal of the judgment.’ (California Civil Procedure During Trial (Cont.Ed. Bar 1960) § 13.26.) ”

Not only did counsel fail to make an offer of proof, his query was obviously faulty. As Justice Gargano wrote for a unanimous Court of Appeal in this case ( 65 Cal.Rptr. 616 , 622), “ [I]t is evident from counsel’s question that he was not attempting to lay a foundation to show a latent ambiguity, nor was he attempting to prove that the words used in the contract were used in some special or technical sense. To the contrary, counsel’s question was seemingly an attempt to change, vary or add to the terms of the agreement. Hence the trial court properly sustained the objection. ’ ’

Once again this court adopts a course leading toward emasculation of the parol evidence rule. During this very year Masterson v. Sine (1968) 68 Cal.2d 222 [ 65 Cal.Rptr. 545 , 436 P.2d 561 ], and Pacific Gas & Elec. Co. v. G. W. Thomas Brayage etc. Co. (1968) ante, p. 33 [ 69 Cal.Rptr. 561 , 442 P.2d 641 ], have contributed toward that result. Al *532 though I had misgivings at the time, I must confess to joining the majority in both of those cases. Now, however, that the majority deem negotiations leading to execution of contracts admissible, the trend has become so unmistakably ominous that I must urge a halt.

It can be contended that there may be no evil per se in considering testimony about every discussion and conversation prior to and contemporaneous with the signing of a written instrument and that social utility may result in some circumstances. The problem, however, is that which devolves upon members of the bar who are commissioned by clients to prepare a written instrument able to withstand future assaults. Given two experienced businessmen dealing at arm’s length, both represented by competent counsel, it has become virtually impossible under recently evolving rules of evidence to draft a written contract that will produce predictable results in court. The written word, heretofore deemed immutable, is now at all times subject to alteration by self-serving recitals based upon fading memories of antecedent events. This, I submit, is a serious impediment to the certainty required in commercial transactions.

I would affirm the judgment.

McComb, J., and Burke, J,, concurred.

Respondent’s petition for a rehearing was denied December 11, 1968. McComb, J., Mosk, J., and Burke, J., were of the opinion that the petition should be granted.