Altaïr is not ready to believe that someone's shaken faith is so easily healed, but it is his habit not to pry unless it's in the scope of his work. Old habits are hard to break. He was Al Mualim's best student, and Al Mualim did not have time for his emotional outbursts. Altaïr judges Paul to have mastered it and folds up his own expression neatly without moving, like a closing book.

"That is good. I would have suggested a walk in fresh air otherwise." It's a little bit of a deflection, but he can't be sure Paul is ready for further discussion. Even if he obliquely explained the maxim in so many words, there is a difference between knowing and understanding.

He relinquishes the books with calloused hands. "If you can find one, will they let me take a--they call it a pencil, but it is not a brush."

The origins and roots of words guide him, but not precisely. He's already been writing Arabic in ink with his qalam, so he must have a different use in mind for a pencil.