concurring in the result.
The judgment of the trial court must receive its basic test in a determination of whether or not it was correct in saying “the first right of refusal granted to Plaintiffs in the Agreement for Warranty Deed is enforceable.” Viewed abstractly as of the date of the agreement, October 22, 1964, the right to purchase contained in para*653graph eleven would seem to be so uncertain and ambiguous as to render it unenforceable. Not only are the words “move from the premises” indefinite and subject to more than one interpretation but more confusing is the phrase “termination of ownership, either by gift, bequest or sale.” This latter appears to be so contradictory in terms as to be entirely meaningless. For example, it could scarcely be assumed that defendants under any circumstances could have intended to make a gift of the real property to plaintiffs, yet under a literal interpretation of the mentioned phrase if the defendants made a move to give the property to anyone other than plaintiffs they would have been required to give it to plaintiffs. Even if a less literal construction of the phrase were to be adopted so that defendants before they could make a gift or a so-called bequest to anyone would be required to sell it to plaintiffs, the price would be left so indefinite as to create a serious doubt as to the agreement’s validity. This court has held that incompleteness and uncertainty in a contract to convey land are fatal to a claim for specific performance. Metcalf v. Hart, 3 Wyo. 513, 27 P. 900, 904, 31 Am.St.Rep. 122 (affirmed 3 Wyo. 513, 31 P. 407, 31 Am.St.Rep. 122). However, an adjudication as to the fatality of an ambiguous or indefinite contract may be affected by the subsequent conduct of the parties. Where contracting parties have given it a practical construction by their conduct, such treatment may be considered by the court in interpreting the contract, ascertaining its meaning, and resolving the mutual intentions of the parties at the time the agreement was made. Such conduct is entitled to great weight in determining the interpretation of the instrument. Baker v. Jones, 69 Wyo. 314, 240 P.2d 1165, 1171; Wyoming Abstract & Title Co. v. Wallick, 64 Wyo. 458, 196 P.2d 384, 386; 17A C.J.S. Contracts § 325(1). Considering the acts of the parties in the instant case, the trial court’s holding that paragraph eleven of the agreement was enforceable cannot be seriously questioned. In that regard, the evidence concerning the deed to the 2.79 acres by Mrs. Edmonds to her daughter, the letter from the daughter’s attorney offering to sell the property to plaintiffs for the sum of $21,000, the deed from the daughter back to Mrs. Edmonds, and the filing of the notice of the first right of refusal by plaintiffs, stating, “whenever the * * * property shall be disposed of by its present owner or owners, whether by gift, bequest or by sale, it shall be disposed of subject to our first right of refusal * * *” (regardless of its legal effect), are pertinent. Thus, I can agree with the prevailing opinion that the trial judge’s ruling on parol evidence is pivotal; and I concur in the determination to return the cause so that testimony may be adduced regarding the matter of a trust.