I don’t buy jeans frequently enough to buy the same kind twice. By the time I’m ready for a new pair of jeans, whatever I’ve been wearing is unavailable, out of style, or both.Of course there are sizes on jeans, but the sizes mean nothing. They are only intended to provide some sort of rough orientation. It would be like saying you know how to find your grandmother’s house in Texas because you know how to get to Texas. Chances are, you are nowhere close. But even if I find a size that fits, I will face difficulties.Jeans with a waistband that comes anywhere near the waist are called “high-rise” jeans, though they used to be called “mom jeans” because “low-rise” jeans were popular for a long time. In order to keep selling new jeans, the low-rise got lower and lower until the zipper was approximately one inch long and its purpose was difficult to ascertain.The obvious problem with this design is that if you try to hang something off the widest part of your body, there isn’t much incentive for it to stay there.Wearing these jeans meant constantly pulling them up before they slipped any farther down. But for a long time these were about the only jeans you could buy, and so I went along with it and joined the legions of women hiking up their jeans as they walked down the street.The only reason low-rise jeans defied gravity at all was because they had spandex in them. This became more and more extreme until some jeans had no denim left in them at all. These are called “jeggings,” an unholy union between leggings and jeans. Designed to be mistaken for jeans from a distance, they were really just elastic pants in disguise.I am not opposed to a little spandex. My husband, Peter, wears “selvage” jeans, which are made with denim of the original heavy weight, when jeans were intended for doing hard work—even harder than walking down the street trying to keep your pants up. Peter bought me a pair, but I have not worn them. New selvage jeans are so stiff I can’t bend my knees or sit down. If I wore them for an evening out, I’d have to be propped up in a corner.“They’ll get softer as you wear them!” Peter insists. I’m not sure I’ll live that long.But because low-rise jeans were popular ...