Etiquette guides get a bad rap for being arbitrary rules that excluded one class of people from the next. While there may be a few of these oddities on the books, most rules are suggestions that made perfect sense at some point in time. With a little historic sympathy, one can sleuth out the reason behind the seeming madness.

Take the rule that it is considered impolite to cut your salad. First, I would have more sympathy with this idea if 90% of the salads I ordered at a restaurant actually had the leaves torn in pieces a little smaller than my face. The modern understanding of this is that leafy greens taste better if torn, rather than the slight bruising of the leaf that happens when sliced. But this old wives’ tale has been dis-proven time and again.

But there is a practical reason that came long before our seemingly finely tuned palettes. Before the invention of stainless steel, the blades of a silver knife were forged of steel, since silver is too soft of a metal for a cutting blade. If anyone is familiar with the first season of Julia Child’s cooking show, The French Chef, you know her opinions about carbon steel knives.

She holds forth on the inferior cutting edge of a stainless steel knife, but she also talks about how the carbon steel blades blacken and stain with cutting certain foods. Acidic foods such as lemons and tomatoes are frequently coupled with lettuce in a salad. Lettuce itself is in the middle of the pH scale but who wants to be the guest who turned your hostess’s sterling set black? So it became bad form to cut your salad. Science has brought us our shiny stainless steel, but our human habits can be slower to change, especially when we can hear our ancestors whispering into our ear at the dinner table.