1. “Tlie rule is well settled that where the parties have reduced to writing what appears to be a complete and certain agreement, importing a legal obligation, it will, in the absence of fraud, accident, or mistake, be conclusively presumed that the writing contains the whole of the agreement between the parties; and parol evidence of prior, contemporaneous, or subsequent conversations, representations, or statements will not be received for the purpose of adding to or varying the written instrument.” 2 Mechem on Sales, § 1254; Civil Code, § 5201.
2. Where a promissory note is given for the purchase-money of a mule, which is unambiguous and unconditional, and contains no warranty of the soundness of the mule, no express warranty can be added to the note by parol; and a plea which set up an express warranty, alleged to have been made by parol contemporaneously with the execution of such a note, was properly stricken on demurrer. Bullard v. Brewer, 118 Ga. 918 (45 S. E. 711) ; Seitz v. Brewers’ Refrigerator Co., 141 U. S. 510 (12 Sup. Ct. 46, 35 L. ed. 837) ; 2 Mechem on Sales, § 1254.