"A picture is worth a thousand words" is another of these supposed �quotes' that never was...rather like Coleridge's "Water, water everywhere but not a drop to drink"! (What the poet actually wrote was "...nor any drop to drink.") Basically, it's a misquote, in other words.
You'll see claims that this is a Chinese proverb - perhaps by Confucius - or that it's a quote from Napoleon. Neither is truly the case. There is a similar ancient Chinese saying, but it actually translates as: "Hearing a hundred times is not as good as seeing once." And what Napoleon actually said was: "Un croquis vaut mieux qu'un long discours." This translates as: "A sketch is worth more than a long speech." Both close...but no cigar!
To get to grips with the actual words we're concerned with, we need to go back only to the 1920s. In December 1921, the magazine �Printer's Ink' contained an advertisement by Frederick R Barnard's company which used the phrase: "One look is worth a thousand words." In March 1927, the same magazine contained another Barnard advertisement saying: "One picture is worth ten thousand words." As happens with many such catch-phrases, these two melded into one in the public's consciousness as: "A picture is worth a thousand words." The fact remains, though that nobody - apart from the first guy to get it wrong and everyone else since! - ever actually said/wrote that! Even Barnard himself apparently claimed it was a Chinese proverb, but it is really no more than a pair of joined-up advertising slogans! And - in the form we use it now - it's no more than about 70 years old, despite similar and very much older phrases.