You have to take the long view. First, when Moses came down from Mt. Sinai, man has already progressed to the point where a commandment against cannibalism was no longer necessary. And, second, it's like pissing on a boulder. For the first few thousand years, you don't see any effect. But after that, you start to see a definite impact.
I. F. StoneWhen you're young, you get blamed for crimes that you didn't commit. When you are old, you get credit for virtues that you never had. I guess it all evens out in the end.
I. F. Stone