The latest political kerfuffle revolves around an expression Barack Obama used at a campaign event on Tuesday: "You can put lipstick on a pig, but it's still a pig." Putting aside the accusation from John McCain's camp that this had something to do with vice-presidential nominee Sarah Palin, the saying has a fascinating historical background, and I had a chance to delve into this history for Slate's "Explainer".

Doing research for the Slate piece, I was surprised to see how far back similar piggish proverbs go. Everybody knows "you can't make a silk purse out of a sow's ear," suggesting that something without inherent value can't be transformed into something valuable. (Proponents of "upcycling" may beg to differ.) That saying has been traced back to 1579, in the English satirist Stephen Gosson's Ephemerides of Phialo: "seekinge..too make a silke purse of a Sowes eare, that when it shoulde close, will not come togeather." Even earlier than that is this quote from 1518, in Alexander Barclay's Eclogues: "None can..make goodly silke of a gotes flece." Whether you start with a sow's ear or a goat's fleece, you just can't make silk without good old-fashioned sericulture.

Silk figured in later sayings too, such as "A hog in a silk waistcoat is still a hog," from Charles H. Spurgeon's 1887 collection of proverbs, The Salt-Cellars. (There's a similar expression in Spanish: Aunque la mona se vista de seda, mona se queda: "Even if the monkey dresses in silk, it is still a monkey.") Much later, in 1964, a columnist for the African-American newspaper The Pittsburgh Courier quoted the aphorism, "You can't put silk socks on a pig." Subsequent allusions to pig beautification moved from silken clothes to various cosmetic changes. Lexicographer Grant Barrett uncovered this quotation in the Jan. 31, 1980 edition of the Quad-City Herald of Brewster, Washington: "You can clean up a pig, put a ribbon on its tail, spray it with perfume, but it is still a pig."

According to the newspaper databases, people didn't start focusing on lipstick as emblematic of superficial improvement until the 1980s. In the Slate piece I cite a 1985 Washington Post article quoting a San Francisco radio personality who felt that renovating Candlestick Park would be like "putting lipstick on a pig." The Post quotation was first noted on the American Dialect Society mailing list a few years ago by inveterate word sleuth Barry Popik, who also observed that the "lipstick" expression had moved beyond pigs to other members of the animal kingdom. Other creatures to get the lipstick treatment in recent years have included bulldogs, chickens, frogs, donkeys, and snakes. All of them would look pretty funny in Revlon, apparently.

But pigs and hogs have been ascendant in the "lipstick" sayings, and for that we may have Texan politicians to thank. As mentioned in Slate, Ann Richards liked to use the expression when she was governor of Texas in the early 1990s, throwing in colorful elaborations like calling the pig "Monique." But her fellow Texan Democrat, Jim Hightower, beat her to it. In 1986, when he was Texas Agricultural Commissioner, he had this to say about the resignation of John Block, Reagan's agriculture secretary: "No one is fooled by this purely cosmetic change. It's like putting lipstick on a pig."

Two decades later, the pig-in-lipstick sentiment has moved from folsky Texanism to the center of a heated political debate. A few months ago we had Bitter-gate and Sweetie-gate, and now we've got Lipstick-gate. Wherever you stand on the latest squabble, it's always good to be armed with some historical context.