If someone offers you a piece of cake or pie...

Martin Parr, Untitled (meringue) from the series British Food, 1995 [via]

"What cannot be taken with the fingers should be taken on your plate. If someone offers you a piece of cake or pie, take it on a spoon or plate, or take what is offered on a spoon and, placing the food on your plate, return the spoon. If what is given is rather fluid, take it on a spoon for tasting and return the spoon after wiping it on a napkin. It is equally impolite to lick greasy fingers or to wipe them on one's tunic: you should wipe them with a napkin or cloth. To consume whole pieces of food at a gulp is for storks and buffoons."

- Desiderius Erasmus, "On Good Manners for  Boys," 1530
 Lapham's Quarterly: Food, Summer 2011