They had been talking about astrology, a forbidden science that was not pursued...

They had been talking about astrology, a forbidden science that was not pursued in the cloister. Narcissus had said that astrology was an attempt to arrange and order the many different types of human beings according to their natures and destinies. At this point Goldmund had objected: "You're forever talking of differences - I've finally recognised a pet theory of yours. When you speak of the great difference that is supposed to exist between you and me, for instance, it seems to me that this difference is nothing but your strange determination to establish differences."
Narcissus: "Yes. You've hit the nail on the head. That's it: to you, differences are quite unimportant; to me, they are what matters most. I am a scholar by nature; science is my vocation. And science is, to quote your words, nothing but the 'determination to establish differences.' Its essence couldn't be defined more accurately. For us, the men of science, nothing is as important as the establishment of differences; science is the art of differentiation. Discovering in every man that which distinguishes him from others is to know him.