 wrote their names in cartouches, an oval, a big oval, and you'd write your name in that, and that would say you're king. And they figured that the name in the cartouche must be Ptolemy also, because they wrote it in Greek, it's Ptolemy, and they knew the same thing was written in hieroglyphs, so Ptolemy must be the name in the cartouche. And that's how they figured out the alphabet. The first hieroglyph in the cartouche was a rectangle, actually.