"You have a strange way about you, Dr. Grumman. You ever spend any time among the witches?"
"Yes," said Grumman. "And among academicians, and among spirits. I found folly everywhere, but there were grains of wisdom in every stream of it. No doubt there was much more wisdom that I failed to recognize. Life is hard, Mr. Scoresby, but we cling to it all the same."
"And this journey we're on? Is that folly or wisdom?"
"The greatest wisdom I know."
"Tell me again what your purpose is. You're going to find the bearer of this subtle knife, and what then?"
"Tell him what his task is."
"And that's a task that includes protecting Lyra," the aeronaut reminded him.
"It will protect all of us."

Lee Scoresby and Stanislaus Grumman in Ch. 14 : Alamo Gulch - His Dark Materials - The Subtle Knife (1997)