Mary Greer (defendant) owned a tract of land and a nonparticipating royalty interest in three other adjacent tracts of land. She executed a royalty deed to Steger Energy Corp. (Steger). The first sentence of the deed conveyed a very specific tract of land called the SixS Frels Unit. The fourth sentence of the deed stated: “In addition to the above described lands, it is the intent of this instrument to convey, and this conveyance does so include, all of grantors [sic] royalty and overriding royalty interest in all oil, gas and other minerals in [Wharton County], whether actually or properly described herein or not, and all of said lands are covered and included herein as fully, in all respects, as if the same had been actually and properly described herein.” Essentially, the deed in the first sentence purports to grant a very specific tract of land, and in the fourth sentence purports to grant all of Greer’s royalty interests in the county. It was later learned that Greer did not actually own the tract she purported to convey in the first sentence. Steger sold the conveyed interest to J. Hiram Moore, Ltd. (Moore) (plaintiff). Moore brought suit against Greer to establish the parties’ respective land rights. Greer maintained that she never intended to convey all of her royalty in Wharton County, but that with the fourth sentence, she intended to convey “small unleased strips adjacent to” the SixS Frels Unit. The trial court granted Moore’s motion for summary judgment. The court of appeals reversed. Moore appealed.