Ever wonder where the terms upper and lower case come from? I, frankly, didn’t, but Philip Gaskell’s A New Introduction to Bibliography (which, as the title might lead you to believe, is exhaustive and frequently exhausting) answers the unasked question anyway.
As it turns out, the origin of these terms is quite simple: when 16th-century printers laid out the cases in which they stored their types, they put the bigger letters in the top of the case, the smaller in the bottom. Considering there was usually only one person per printing press responsible for setting the type (the compositor), anything to add method to the madness was, I’m sure, necessary.
For similar reasons, this is also why we should forgive poor Renaissance spelling. Shake-spear, Shaxberd – what’s the difference, really?