TATE, Justice ad hoc.
Plaintiff appeals from district court judgment dismissing his suit to have declared expired an option to purchase certain property in Orleans Parish, granted by him on May 9, 1952 to defendant, Creole Land Company, Inc. (“Creole”) ;1 and also from the trial court’s decree granting, in accordance with Creole’s reconventional demand, specific performance of the option agreement in question.
'By third party petition Creole joined as third party defendants Joe W. Brown and his wife, Dorothy Dorsett Brown, who on December 9, 1954 had acquired from plaintiff Zemurray certain immovable property, including that allegedly subject to Creole’s option to purchase. These third party defendants likewise appealed from the trial court’s judgment, which ordered them to join in the specific performance ordered by the court by Zemurray of the sale of the land subject to the option agreement.2
[627]*627Creole did not comply with one of the conditions of the option agreement by the date provided by said clause, and the substantial question of this appeal is whether (as appellants contend) non-compliance with this condition by the stated date ipso facto terminated any rights of Creole under the option agreement, or whether on the contrary (as appellees contend) after Creole’s default in this regard, Zemurray was required, prior to a tender of performance by Creole, to put the latter in default by judicial demand to dissolve the contract on that account, in order to obtain as of right the dissolution of the option agreement. It is further urged by the appellees that, in any event, the plaintiff waived timely performance of this condition and/or is estopped to urge invalidity on account of this alleged default of the option agreement.
The option agreement, from Zemurray to Creole of May 9, 1952, granted, for the sum of $500, the latter the option until May 9, 1954 to purchase approximately 677 acres of land in Sections 20, 21, and 22 of the New Orleans Lakeshore Land Company, at the price of $750 per acre, under certain specified terms. Certain “conditions precedent” to the exercise of the option granted by the instrument were imposed by Clause 6, 7 and 7A, by which no rights under the option were to be acquired by 'Creole unless certain acts were performed with regard to adjoining land in Section 19 which Zemurray had earlier (on June 21, 1950) sold to the Pines Construction Co., Inc. (“Pines”) and with regard to-the indebtedness still owed by Pines to Zemurray therefor.3
Clause 7 required the completion of one hundred additional residences upon the Pines tract, with sewerage facilities, prior to May 9, 1954, the terminal date of the option, as condition precedent to exercising the option; as a similar condition, Clause 7A required cancellation of tax liens affecting this tract (which tract was also subject to Zemurray’s unpaid vendor’s lien.)
The meaning and effect of the other “condition precedent”, Clause 6, is the central issue of this controversy. This clause provides:4
“6. A condition precedent to the exercise of the option granted hereby is the acquisition by purchaser [Creole] from vendor [Zemurray] of, or the payment of the balance due on, the [629]*629note held by vendor and made by Pines Construction Company, Inc. for $149,-320.00 dated June 21, 1950 and secured by mortgage and vendor’s lien on groves in Section 19 of the New Orleans Lakeshore Land Company Tract, and THIS OPTION WILL TERMINATE UNLESS SAID ACQUISITION OR PAYMENT HAS BEEN MADE ON OR BEFORE OCTOBER 21, 1952. Vendor [Zenmrray] reserves' the right to foreclose or take other legal action as vendor may deem advisable in the event of default on the mortgage and vendor’s lien securing payment of the said note, provided if vendor proposes to foreclose ptirchaser [Creole] will be given five days written notice before institution of foreclostwe and in which five day period the purr chaser may cure the default.” (Capitalization and italicization ours.)
We are unable to see the ambiguity in this clause which appellees profess to discover, nor to find the meaning assigned to it by them.
The clause states that Creole must purchase or pay before October 21, 1952 the mortgage note due by Pines for the purchase of some adjacent property,5 as a condition precedent to acquiring the right to exercise the option to purchase the present property. The italicized second sentence of the clause, rather than indicating (as appellees profess themselves to believe) any intention to confer rights with regard to payment of the Pines’ mortgage after October 21, 1952, simply in its context grants Creole the privilege of receiving five days notice and curing the default if before October 21, 1952 Zemurray wished to foreclose or to take other legal action with regard to the mortgage note owed him by Pines.
Much of the appellees’ argument that the clause is ambiguous or contradictory with other agreements between the parties is based upon an incorrect assumption that Clause 6 somehow extended the date of payment as to Pines of the mortgage note owed by Pines.6 To the contrary, of course, Zemurray specifically reserved therein his right to foreclose or sue upon the Pines’ note, although agreeing as to Creole to give the latter firm five days no[631]*631tice before taking such action against Pines.7 The obvious intent of the italicized second sentence was to provide for Creole’s rights vis á vis Zemurray should the latter decide in the interval before October 21, 1952 to foreclose upon the Pines’ mortgage, the $99,000 balance of which would become due on June 21, 1952; not to affect any right Zemurray had against Pines, which latter firm was not a party to the agreement.
Likewise, we are unable to find that two side agreements between Zemurray and Creole evidenced by letters of the same date (May 9,' 1952) as the option agreement between them, change the clear meaning of the option clause in question nor convert it into ambiguity. .The letter from Creole to Zemurray introduced in evidence as “Creole 10”, simply stated that the “option will not be delivered and become effective” unless certain acts were accomplished which were not inconsistent with the above clause or with the option agreement.8 “Creole 11”, a letter from Zemurray to Creole,9 simply stated Zemurray’s agree[633]*633ment to execute for the sum of $26,953.09 a partial cancellation of his mortgage upon certain of the property sold by him to Pines, without reference to whether or not Creole acquired any rights under the option agreement in question.10
Although under Clause 6 acquisition or payment by Creole of the Pines note (upon which there was then a balance due of approximately $99,000) by October 21, 1952 was required before Creole could acquire any rights under the option agreement, a balance of $64,654.62 (plus $3,228.-23 attorney’s fees) was not paid until April 8, 1954, several smaller payments having been made earlier.11 On April 3, 1954, prior to such payment, Zemurray’s attorney had by letter to Creole demanded a duly executed release of the option in question as it had “terminated on October 21, 1952.” (P-2; Tr-103) Following Creole’s failure [635]*635to do so, the present suit was filed on April 26, 1954.
Appellees successfully contended in the trial court that the condition above set forth as Clause 6 is what is known to our civil law as a resolutory condition, non-compliance with which terminated or revoked as of right Zemurray’s obligations under the option contract only if (being an event depending on the will of a party to the agreement) Zemurray had formally placed Creole in default by filing suit before Creole’s performance of the condition by paying on April 8, 1954 the balance due upon Pines’ mortgage note. LSA-C.C. Arts. 2045,12 2046,13 2047;14 Southport Mill v. Ansley, 160 La. 131, 106 So. 720; Gayden v. Louisville, Nashville, New Orleans and Texas R. Co., 39 La.Ann. 269, 1 So. 792.
Contrariwise appellants contend that the condition expressed by Clause 6 — the payment or acquisition of the Pines’ mortgage on or before October 21, 1952 — is what is known to our civil law as a suspensive condition the occurrence of which was necessary to initiate any obligation on the part of Zemurray as set forth in the option agreement; that since this condition never occurred, Zemurray is not obligated under the agreement to sell the property to Creole. LSA-C.C. Arts. 2043 ;15 Stack v. De Soto Properties, Inc., 221 La. 384, 59 So.2d 428; Conklin v. Caffall, 189 La. 301, 179 So. 434; Standard Oil Co. of Louisiana v. Milholland, 167 La. 707, 120 So. 59; see also, City of New Orleans v. Texas & P. Ry. Co., 1898, 171 U.S. 312, 18 S.Ct. 875, 43 L.Ed. 178.
[637]*637The distinction between a suspensive and a resolutory condition is summarized by LSA-C.C. Art. 2021:
“Conditional obligations are such as are made to depend on an uncertain event. If the obligation is not to take place %mtil the event happen, it is a suspensive condition; if the obligation takes effect immediately, but is liable to be defeated when the event happens, it is then a resolu.tory condition.” (Italics ours.)
The general distinction between suspensive and resolutory conditions is described in 15 C.J.S. Condition, p. 810, as follows:
“A condition is suspensive (corresponding to the condition precedent of the Anglo-American law) when its occurrence is necessary to initiate am, obligation or juristic act; when the latter is terminated by its occurrence it is called resolutive (resolutoire) and corresponds to the condition subsequent of Anglo-American law.” (Italics ours.)
See, to the same effect, our recent decision in Dufrene v. Tracy, 232 La. 386, 94 So.2d 297.
Appellees urge that under this distinction, since by the present option agreement Zemurray granted Creole the option to buy the property herein until May 9, 1954, the condition of Clause 6 that the option would terminate unless the Pines mortgage were paid before October 21, 1952, is by its terms a resolutory condition because non-performance thereof defeats or dissolves or terminates the option previously granted by Zemurray.
The appellees’ contention that non-performance is resolutory as dissolving an existing obligation by Zemurray (namely, the obligation to sell Creole the land in question if the option were accepted by May 9, 1954) overlooks that no such obligation existed; and the cases relied upon by appellees concerning obligations to sell which the obligor sought to have dissolved because of the obligee’s non-performance timely (Honore v. Jones, 180 La. 109, 156 So. 191; Southport Mill v. Ansley, 160 La. 131, 106 So. 720; cf. also, Johnson v. Shreveport Properties, Inc., 213 La. 485, 35 So.2d 25)16 are distinguishable on that account, Standard Oil Co. of Louisiana v. Milholland, 167 La. 707, 120 So. 59. For an op[639]*639tion, such as is involved in the present case, is merely “the * * * option [to the grantee] to accept or reject, within a stipulated time, an offer or promise to sell,” LSA-C.C. Art. 2462; until accepted in accordance with its terms, neither party is obligated to performance thereof. LSA-C.C. Art. 2462; Moresi v. Burleigh, 170 La. 270, 127 So. 624; Bermuda Stock Farms Co. v. Gilliland Oil Co., 155 La. 949, 99 So. 708. There is thus no obligation to sell to be dissolved by non-performance timely.
Under the option agreement between the parties, the obligation of Zemurray here sought to be enforced — his alleged obligation to sell Creole the land in question for the stated consideration— only came into existence if certain things were done, including that: (1) notice be given in writing to Zemurray of the acceptance of the option by 5 :00 P.M., May 9, 1954; (2) Pines’ mortgage be paid or acquired by October 21, 1952; (3) 100 residences be completed on Pines’ land by May 9, 1954; and (4) all federal, state, and city tax liens affecting Pines’ land be cancelled. The occurrence of these conditions was necessary to initiate Zemurray’s obligation to sell the land; they were conditions suspensive of the obligation of Zemurray to sell the land upon Creole’s acceptance by May 9, 1954. Rather than terminating any such obligation, Creole’s failure to pay or acquire the Pines mortgage by October 21, 1952, prevented its coming into existence. Cf., Standard Oil Co. of Louisiana v. Milholland, 167 La. 707, 120 So. 59. It was just as much a condition exacted by Zemurray to be fulfilled as precedent to any obligation on his part to sell the land, that Creole accomplish such timely payment of the Pines mortgage by October 21, 1952, as it was that Creole make timely acceptance of the option in writing by May 9, 1954; and failure to fulfill either condition timely would prevent the initiation of any obligation on the part of Zemurray to sell the land.
The record contains a great deal of parol and extrinsic evidence admitted over plaintiff’s objection to prove that the intent of the parties, as also manifested by their subsequent conduct, was otherwise. The admission of this evidence was incorrect. It is only where the instrument is ambiguous as to the intent of the parties that such evidence is admissible. Dufrene v. Tracy, 232 La. 386, 94 So.2d 297. Where, as here, the intent of the parties as evidenced by the instruments executed by them is free from ambiguity, parol or extrinsic evidence is inadmissible as an aid in the construction to vary the terms thereof. Weber v. H. G. Hill Stores, Inc., 210 La. 977, 29 So.2d 33; Standard Oil Co. of Louisiana v. Futral, 204 La. 215, 15 So.2d 65; cf., Rudman v. Dupuis, 206 La. 1061, 20 So.2d 363.
(The extrinsic evidence incorrectly admitted shows that Pines, following his ac[641]*641quisition of the Section 19 land from Zemurray in 1950, fell into great financial difficulty, and that Zemurray in an effort to assist Pines and Pines’ creditors, many of whom were Zemurray’s personal friends, cooperated with the refinancing of Pines’ operations through the vehicle of Creole by giving the latter a very favorable option to purchase the adjacent 677 acres here in question; it does not show, however, that Zemurray did not, as a part of the consideration for his cooperation in granting the favorable option, desire other than that the Pines mortgage be paid or purchased on or before October 21, 1952. That Zemurray may also have wished to avoid, if possible, his reacquisition by foreclosure of the Section 19 land previously sold to Pines, and that Zemurray may have hoped that by the development of Section 19 land his adjacent holdings would become more valuable, does not alter his having exacted, as a condition precedent to the acquisition by Creole of its valuable rights under the option agreement, the payment or purchase by October 21, 1952 of the Pines mortgage.17 And although it may be stated that a fair deduction from this evidence is that, in order to assist the parties, Zemurray did not intend to foreclose upon the Pines mortgage before October 21, 1952, there is no evidence whatsoever that he agreed not to do so; and indeed, the italicized second sentence of Clause 6 above quoted demonstrates the complete absence of any such agreement upon his part.)
Pretermitting whether or not, under the facts of this case, parol or other extrinsic evidence was admissible to prove any waiver, by permitting performance, of the requirement that the Pines mortgage be [643]*643paid or acquired by Creole before October 21, 1952,18 the facts do not so show the same, nor do they show that Creole or its agents was ever accorded such extension of the condition of the option.19
Appellees further contend that Zemurray, by accepting from Creole the payment in full of the Pines note subsequent to October 21, 1952, is estopped to claim that the option agreement was terminated by Creole’s failure to pay or acquire such note on or before such date; and/or that such conduct on Zemurray’s part waived compliance by Creole with this condition. Pretermitting discussion of appellants’ argument that an extension of time for performance of an agreement affecting the title to real estate must be in writing and cannot be established by estoppel, cf., Harrell v. Stumberg, 220 La. 811, 57 So.2d 692, such [645]*645contentions find no support in the present record.
The argument thus advanced with seeming sincerity assumes that Creole paid the Pines mortgage to Zemurray with its own funds and solely with the hope of securing the benefits of the option agreement in question.20 However, such a contention completely overlooks the agreements between Pines and Creole contained in the Agreement to Sell and Option to Buy Property of May 19, 1952 (Creole 22; Tr-212), and of the Sales by Pines to Creole of its property in Section 19 previously acquired from Zemurray dated May 21, 1952 (P-9, Tr-116) and dated April 8, 1954 (P-10, Tr-132).
Under the first agreement described (Creole 22), Pines agreed to sell and Creole to buy certain of the Section 19 property for $65,478.09 (of which a certain portion was reserved for payment of Zemurray’s mortgage) and Creole was given an option to buy the remainder of the Pines property. Paragraph 7 thereof states that, as condition precedent to the options granted by Pines to Creole to purchase Pines’ land in Section 19, “Creole agrees to acquire by purchase or assignment on or before October 21, 1952” the mortgage note in favor of Zemurray.
By the second instrument described, the sale dated May 21, 1952 (P-9), Pines sold Creole certain of the land it had acquired from Zemurray for the sum of $65,478.09, of which $38,525 was paid in cash to Pines by Creole and of which the remainder ($26,-953.09) was reserved from the purchase price since, as stated, Creole “will be required to pay the said sum of $26,953.09 to the holder of said mortgage note”, i. e., Zemurray. (Tr-127.)
By the third instrument, the sale of April 8, 1954 (P-10), Creole acquired all or most of the remaining Pines land for the sum of $120,370, for which a promissory note of $37,300 was furnished and the remainder ($83,000) noted as paid in cash. (By letter of April 30, 1954, P-14, Tr-148, from Creole to Pines, the consideration was modified and the balance of the purchase price was paid to Pines.) This instrument contains the statement as to disposition of the cash consideration due by Creole to Pines, Tr-137:
“Purchaser takes cognizance that there is recorded against the property herein the vendor’s lien and mortgage [647]*647to secure payment of a certain original promissory note in the sum of $150,-320.00 (on which there is a balance due of $62,657.83 plus 3yí% per annum interest from June 21, 1953 to date) per act before F. H. Lapeyre, Notary Public, dated June 21, 1950, recorded in M.O.B. 1798, Folio 227, Parish of Orleans, which said obligation has been paid in full by purchaser from the proceeds of this sale.
“Purchaser likewise takes cognizance that there are certain U. S. Government tax liens recorded against the property herein, and there has been deposited by purchaser with the undersigned Notary Public the sum of $17,-000.00 cash with which to secure release of said tax liens.”
Thus the payment by Creole to Zemurray of these substantial sums of $26,953.09 (P-9) and of $62,657.93 plus interest (P-10) upon the note due by Pines to Zemurray upon which there was a balance due as of May 19, 1952 of $99,393.43 when Creole agreed with Pines to acquire same as a condition precedent to exercising its option to acquire the Pines land (see Creole 22, Tr-218), rather than being payments made independently of any obligation to do so and solely to obtain the benefits of the option granted Creole by Zemurray, were payments which Creole was contractually obligated to make as part of the purchase price it paid Pines to acquire such lands for its own uses and its own subdivision activities. Likewise, when Creole paid the sum of $9,-600 to Zemurray on July 31, 1953, the record indicates that such sum was reserved from the total purchase price received for the re-sale of some of the Pines land to a third person, in order to secure a cancellation of the mortgage held by Zemurray against such land in order to deliver a good title to the purchaser. (Tr. 403^-04; see P-11, Tr. 138.)
It should be noted that, except for the final payment satisfying the mortgage liability in full and releasing as to the remainder of Section 19 acquired by Creole, each time Creole paid Zemurray the principal upon the Pines note, it did so from the proceeds received from the profitable re-sale 21 by itself of the land it had acquired from Zemurray’s vendee and in order to obtain a partial cancellation of the mortgage held by Zemurray affecting the property thus sold by itself and to deliver a good title to its own vendees. (P-4, Tr. 105 ; P-5, Tr. 108; P-6, Tr. Ill; P-11, Tr. 138.)
Likewise the interest payments22 (insofar as not possibly paid by Pines through [649]*649Creole, cf., P-7, Tr. 114) and the cancellation of any liens against the land (insofar as not from proceeds due Pines which Creole obligated itself to pay to the lienors as part of the consideration for buying Pines’ lands, cf. Tr. 137) must be viewed— against Creole’s claim of Zemurray’s estoppel thereby — in the light of Creole’s interest of preventing foreclosure upon (see Tr. 410) and claims against the lands acquired by it from Pines (or under option to it from Pines) upon which Creole was engaged in subdivision activities on its own account and presumably to make a profit. (See Tr. 391.)
As we stated in Breaux v. Laird, 230 La. 221, 234-235, 88 So.2d 33, 38, 39:
“The doctrine of waiver or estoppel contravenes the legal rights of the person sought to be estopped, * * * Our courts and other jurisdictions universally hold that this doctrine should be applied only in exceptional cases where the application is necessary to effectuate justice or prevent injustice * * * [P]leas of this doctrine can be of no avail to the party urging same unless he has been clearly misled to his detriment or injury by the actions or conduct of the party against whom the plea is urged. * * * ”
We cannot find any such basis for the pleas of estoppel or waiver thus urged before us, and we are unable to see any justification whatsoever for the suggestion that Zemurray was unjustly enriched under the facts above stated by permitting Creole to pay the long overdue mortgage he held against land acquired by Creole.
It should be mentioned that Pines and the creditors of Pines by agreements dated May 19, 1952 (Tr. 47, attached to petition of intervention; and Tr. 212, Creole 22) received Creole’s agreement to pay to Pines and on behalf of Pines’ creditors an over-rider of from $700 — $1650 per acre on any acreage purchased from Zemurray pursuant to the present option. Any rights resulting to Pines or its creditors by such agreement, to which Zemurray was not a party, were of course dependent upon Creole’s valid and timely exercise of the option granted to Creole by Zemurray.
For the reasons assigned, the judgment of the trial court is reversed and set aside. It is now ordered that there be judgment in favor of plaintiff, Samuel Zemurray, and against the defendants, Creole Land Company, Inc. and Edward L. Boesch (successor of Arthur J. Boe), Register of Conveyances for the Parish of Orleans, ordering the cancellation as expired and of no further force and effect from the conveyance records of the Parish of Orleans of a certain option dated May 9, 1952 granted by plaintiff to Creole Land Company, Inc. to purchase certain groves then owned by him in Sections 20, 21, and 22 of the New Orleans Lakeshore Land Company Tract; recorded at Conveyance Book 585, Folio 285. It is further ordered that the judgment in favor of defendant Creole Land Company, [651]*651Inc. upon its'reconventional demand is reversed ánd set aside,'and such reconventional demand is hereby dismissed. It is further ordered that the petitions of intervenors allied with defendant Creole Land Company, Inc. are likewise dismissed. The costs of these proceedings are to be paid by Creole Land Company, Inc. and its allied intervenors.