Many things intellectualoids like me "know" are really detached pieces of information that just imply knowledge. We read essays and reviews and pick up references to works that require a substantial investment of time and intellect to understand. How many of us who make reference to the life of man in a state of nature being "solitary, poor, nasty, brutish, and short" have ever read Leviathan, or anything else by Hobbes?
I know I haven't, and am not likely to. It's just a little intellectual accessory I display to show what kind of person I like to think I am.
Unfortunately, aside from being ludicrously simplified, our intellectual accessories are often wrong.
For example, anyone trying to pretend to a knowledge of gladiators in the ancient world (again, like me) knows that gladiators always said "Ave, Imperator, morituri te salutamus" (Hail, Caesar, we who are about to die salute you) before going out on the sand.
Except they didn't. This phrase is only attested to have been used once, at a naumachia, or naval combat, at Fucine Lake to celebrate the completion of a drainage tunnel. The sailors on the ships supposedly said that phrase, to which the Emperor Claudius jokingly replied "or not", which led the sailors to refuse to fight. How they heard him and made this decision is not clear--it's a big lake and there were nearly 20,000 of them. They were finally persuaded to bloody combat and all was well.
However, the phrase had an afterlife in later eras, in paintings, poems, books, movies, etc., and now represents a casual, hip understanding of gladiatorial combat in the ancient world. It even appears in Heinlein's Glory Road, the person addressed changed to the feminine, since Rufo is addressing Star, the Empress. I remember feeling all cool for recognizing it when I read it as a young man, since Heinlein doesn't explain it. He knew his audience. All of us want to show we know something, but really don't want to put too much work into it. Providing little tidbits like that to the developing intellect is an important and underappreciated function of science fiction novels.
We'll all continue to the use the phrase. But now you can one-up anyone by referencing Fucine Lake, Claudius, and the sparse historical record when the phrase surfaces. That's sure to gain you the respect of your fellows.