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[mirrorshades]

I seem to remember that Last Crusade offered different ways past the various guards -- so by leaving an item behind that you could use, you still had another way to get past. Of course, the other way was usually fighting, so you had to practice up a bit to get really good.

They say that you can make it through the entire game without having to fight at all. However, if you don't have a necessary item or dialogue option for the "non-fight" solution, you have to win with your fists. So in other words, you aren't prevented from winning if you don't have the books... you're just prevented from winning as simply as possible.