In Nelsen v. Farmers Mutual Auto Insurance Co., 4 Wis. 2d 36, 90 N.W.2d 123 (1958), the plaintiff was a district supervisor and agent of the defendant insurance company. Initially, Nelsen worked under an oral agreement. See Nelsen, 4 Wis. 2d at 40-41. After several years of working for the defendant in that capacity, Nelsen was sent a letter that laid out the terms of his employment. See Nelsen, 4 Wis. 2d at 45. Among the terms was that Nelsen was to be paid commissions of 10% on new business and 4% on renewal business. See id. Three years later, the defendant unilaterally changed the terms by issuing a new agreement letter whereby Nelsen would only be paid a 2% commission on renewal business. See Nelsen, 4 Wis. 2d at 56. Nelsen protested the change, but continued working for the defendant under the belief that he and other "old-timers" could continue to work under the old agreements. See Nelsen, 4 Wis. 2d at 46-47. The Court ultimately upheld the jury's finding that Nelsen did not accept the modified terms contained in the defendant's later agreement letters purporting to change the terms of the relationship between the parties. See Nelsen, 4 Wis. 2d at 57. In doing so, the court recognized the rule that "one party to a contract cannot alter its terms without the assent of the other parties; the minds of the parties must meet as to the proposed modification." Nelsen, 4 Wis. 2d at 55.