I run a B/X game for a few guys, most of whom have only played 3E before. It leads to a lot of talk about the change in power level between basic and 3E. One of the things that came up was the somewhat lower attribute modifiers and bonuses.
"Oh man!" I exclaimed. "I bet you guys don't know about percentile strength!"
So, I pulled up the 1E PHB and I was blown away myself to see just how much more powerful 18/00 was compared to plain old 18. A cleric with 18 strength gets +2 damage, while a fighter with 18/00 gets +6. Wow! I remember loving the extra roll being a possibility as a player, and hating the possibility for such a massive bonus as a DM. I don't think it ever came up in play, either way.
Where did this system come from? Was it just invented for AD&D 1E, or was it prefigured in a Dragon article, or what?
UPDATE: Given that aramis pointed out its origin in OD&D's Greyhawk, I doubt we'll find anything on the motivation for it, but if anyone finds that, I would still be quite interested. (Speculation like "Gary wanted to give more damage bonus to strong character" can be omitted, unless we find evidence.)
Best Answer
The first rulebook including it was D&D Supplement 1: Greyhawk, on page 7. This predates AD&D by several years.
It also places it squarely into Gygax's purview.