Mid-word "s" and end-word "s"

Reading Cecil’s column about the different letters of “s” http://www.straightdope.com/columns/read/101/why-did-18th-century-writers-use-f-inftead-of-s
I was a bit surprised that he traced the two s-forms only back to the Romans. I thought (no cite) that the Romans borrowed their letters from the Greeks, who also have one form of Sigmain the middle of the word, and another form at the end (though interestingly, their mid-word s is short and rounded, the end-word sigma is long - the other way round from medieval roman letters).

Wikipedia (I know, second-best to Cecil’s knowledge of paleography) says that the Greeks got their letters from the Phonecians, who had four S-letters for four different sounds, which resulted in two different letters for the same sound in Greek (and Romand, and English).

It’s not that simple.

A) It is generally believed that the Latin alphabet is not directly derived from the Greek alphabet, but from the Etruscan alphabet (which derived from the Greek alphabet).

B) Neither the ancient Romans nor the ancient Greeks used lower-case letters, which were invented in the middle ages. (And the practice of mixing the ancient letters – upper-case – with the medieval letters according to certain rules is even more modern.)

Cecil discussed some facets of the origin of the alphabet in this column: http://www.straightdope.com/columns/read/2696/why-is-the-alphabet-in-alphabetical-order He mentions something about a mix-up of sibilant (s- and z-like) sounds in developing the Greek alphabet from Phoenician but without giving much detail.

That’s quite surprising to me. Yes, the Greeks and Romans used capital letters for inscriptions, because the angular shapes were easier to carve. But for pergament, papyrus or the wax tablets, they used quick handwriting in lower-case. Every reproduction of Platons or Aristoteles writings is in lower-case. Where did you hear that lower-case was invented in the Middle ages? By that time, greek had already died out in the West and replaced by latin, so how could lower-case greek letters be developed then?

This is basic history-of-the-alphabet stuff that you can find in any book or encyclopedia that treats the subject. Both Greek and Latin “lowercase” letters arose in the second half of the first Christian millennium. Greek minuscules are used for modern editions of The Republic for the same reason that Latin minuscules are used for modern editions of The Gallic Wars—the same reason that u is a vowel, v is a consonant, and only s is used in modern editions of Hamlet, and not ſ. Various shorthands existed, but only our “uppercase” shapes were used for formal presentation in ancient times.