Apples and Oranges ...

... are actually pretty damn similar.

How did "like comparing apples and oranges" get to be our standard phrase for indicating that two things are so different as to resist comparison? They're both fruit, typically about the size of a baseball, have a skin and seeds, are mostly water. There are more similarities than differences.

I assumed there was some history to this phrase, some context where it made sense. The only thing I can find is one reference suggesting, "that the phrase appeared as apples and oysters in John Ray's proverb collection of 1670." Okay, that makes a bit more sense. Or at least it works better for what people mean when they say it.

But I suspect it's more like the phrase, "You can't judge a book by its cover." Really? Put a Unix textbook next to a Harlequin romance and I'll bet I can tell you a whole lot about it. That phrase originated in a time when all books were printed with blank bindings, and covers could be applied by the seller or the customer. So back then no, you really couldn't tell a book by its cover.