Open Range - A Thousand Words
In the beginning Costner and Duvall are looking over the landscape, and admiring it. They say that it looks like a picture, and that it is said that "a picture is worth a thousand words". The movie takes place in the late 1800s (1888, I think). The phrase they are quoting from was not thought up until 1921, when it was created as part of an advertising campaign.