We need to imagine as well as measure. - Philip Pullman

The intentions of a tool are what it does. A hammer intends to strike, a vise intends to hold fast, a lever intends to lift. They are what it is made for. But sometimes a tool may have other uses that you don't know. Sometimes in doing what you intend, you also do what the knife intends, without knowing.

There are two great powers,” the man said, “and they’ve been fighting since time began. Every advance in human life, every scrap of knowledge and wisdom and decency we have has been torn by one side from the teeth of the other. Every little increase in human freedom has been fought over ferociously between those who want us to know more and be wiser and stronger, and those who want us to obey and be humble and submit.

The other side’s got an energy that our side en’t got. Comes from their certainty about being right. If you got that certainty, you’ll be willing to do anything to bring about the end you want. It’s the oldest human problem, Lyra, an’ it’s the difference between good and evil. Evil can be unscrupulous, and good can’t. Evil has nothing to stop it doing what it wants, while good has one hand tied behind its back. To do the things it needs to do to win, it’d have to become evil to do ’em.