Huygens’ comparison of Saturn’s size with that of Earth (Tellus) and the Moon (Luna).
Also, an alphabet primer for people who don’t care about the proper alphabetical order. Or about missing half the letters.
Huygens, by the way, is Christiaan Huygens, a Dutch mathematician and astronomer, and the first theoretical physicist. Among other things, he thought light was a wave and that we would find life on Earth-like planets. And while only one of those ideas has been vindicated so far, what’s certain is that he could rock a lace-and-wig combo.