Word peeve: "rein" versus "reign"

Part of the fallout from (a) the culture's increasing dependence on television and visual media, and (b) the stream-of-consciousness writing that infests the Web, is that we're seeing a lot more poor writing.  Excessive amounts, maybe.  Take the confusion between "rein" and "reign" in two common figures of speech.

Oh. You didn't know there was a difference?

"Reign" is what a king does. It's synonymous with "rule".  "Reins" are the leather straps attached to a horse's bridle, which a rider uses to control a horse. Got it? Now let's look at the confusion between the two.

If you are riding across the prairie and you want to let the horse decide where to go, you hold the reins very loosely, with a lot of slack in them, even to the extreme of letting go and leaving them dangling around his neck. That's called giving the horse "free rein."

When you let your kids run around the house like crazy, you may think you're giving them "free reign," because you're letting them be their own bosses. But the original term had to do with horses and reins, not with kings or their subjects.

Back to the horse. If you're galloping across the prairie and the horse is going too fast for your safety or comfort, you slow the horse down by pulling on the reins. The harder you pull, the more abruptly the horse comes to a stop. Because you are pulling the reins tight, we say that you are "reining in" the horse - reestablishing your control over the steed. Other related metaphors, all of which address the assertion of control over an out-of-control agent, are "keeping someone on a short leash" and "putting on the brakes."

There is no "reigning in" somebody. You can't even invent an etymology that goes with that. "Reigning in" makes as much sense as "a short leech" or "putting on the breaks." Don't do it.