Engel's Law

Way less tasty with hot dogs on a summer day than Cole's Law.

Engel might have been a hungry guy. We're talking about Ernst Engel here, a German statistician who lived between 1821 and 1896 (if you created an algorithm to come up with a name for a 19th century German statistician, it would probably spit out "Ernst Engel").

Engel proposed that, as a person's income rises, the proportion of their income spent on food will decline. So the percentage of your income spent on food is going down as income is rising. This fact remains true, even if the person spends a larger total amount on food.

This makes a lot of sense (you might have the law named after you if Engel didn't beat you to it by 150 years). You have to eat, no matter how little you make. Food costs what it costs. So, if you're not making a lot, you have to devote a sizable proportion of your income to food. But as income rises, your need for food doesn't really rise with it.

At a certain point in poverty, you might go without food sometimes, but once that picking-stuff-out-of-garbage-cans-or-going-to-be-hungry threshold is cleared, you really don't need more food. You might eat better food (Red Lobster vs. Long John Silver, for instance), but you're only going to start doing this upgrade after buying the other things you needed when you were spending all your money on, uh...keeping yourself from starving.