We know the Vulcan philosophy comes from Surak, the Klingon way from Kahless, and that Zefram Cochrane is the posterboy for human exploration and ingenuity.
Where do the Rules of Acquisition come from?
Any Grand Nagus who comes up with a rule, really. Gint was supposed to be the original writer, but the rules have grown over the centuries - there's no way to know which ones were written by Gint.
So any Nagus could do whatever they want with the Rules, as long as they're accepted by the Ferengi people. In that episode, this is what Quark says, before he actually reads the new rules:
Quark: Rom.. D'you know what this means?
Rom: Yes. It means we're gonna have to memorize a whole new set of rules...
Quark: No, you idiot.. It means, we'll be the first Ferengi to benefit from Zek's wisdom. The knowledge contained in this book could make us both rich beyond our wildest dreams!
So since any Nagus can add their own wisdom to the book as a short, easily repeatable and rememberable sound bite, the Rules of Acquisition have simply grown over the years as the Naguses (Nagi?) add to it.
I also thought I remember Zek adding a 286th rule during the run of DS9, but I thought it was in Prophet Motive - it wasn't. Oh well.