(A picture is worth a thousand words is a proverb that refers to the idea that complex stories can be told with just a single still image, or that an image may be more influential than a substantial amount of text. It also aptly characterizes the goals of visualization where large amounts of data must be absorbed quickly.
It is believed that the modern use of the phrase stems from an article by Fred R. Barnard in the advertising trade journal Printers' Ink , promoting the use of images in advertisements that appeared on the sides of streetcars. The December 8, 1921 issue carries an ad entitled, "One Look is Worth A Thousand Words."
Another ad by Barnard appears in the March 10, 1927 issue with the phrase "One Picture is Worth Ten Thousand Words," where it is labelled a Chinese proverb. The Home Book of Proverbs, Maxims, and Familiar Phrases quotes Barnard as saying he called it "a Chinese proverb, so that people would take it seriously." Soon after, the proverb would become popularly attributed to Confucius.
Despite this modern origin of the popular phrase, the sentiment has been expressed by earlier writers. For example the Russian writer Ivan Turgenev wrote (in Fathers and Sons in 1862), "A picture shows me at a glance what it takes dozens of pages of a book to expound."
The quote is sometimes attributed to Napoleon Bonaparte, who said "Un bon croquis vaut mieux qu'un long discours," or "A good sketch is better than a long speech". While this is sometimes translated today as "A picture is worth a thousand words," this translation may not predate the phrase's common use in English.