The history behind `Brawny gods just flocked up to quiz and vex him.` is fairly simple – it is used to get all 26 letters of the english alphabet into a short sentence, with 47 characters.
Brawny gods just flocked up to quiz and vex him.
If you look up `The quick brown fox` on Wikipedia you’ll find this is similar to what they say:
> “The quick brown fox jumps over the lazy dog” is an English-language pangram – a phrase that contains all of the letters of the alphabet. It has been used to test typewriters and computer keyboards, and in other applications involving all of the letters in the English alphabet. Owing to its brevity and coherence, it has become widely known.
TypeKit also uses `Brawny gods just flocked up to quiz and vex him.`, among other frases to demonstrate their fonts.