Stalking Darkness (Nightrunner, #2)

by Lynn Flewelling

Some books are available to anyone, others are locked away.” “Why, are they valuable?” asked Alec, thinking of the beautifully decorated scrolls Nysander had lent him. “All books are valuable. Some are dangerous.” “Books of spells, you mean?” Seregil grinned. “Those, too, but I was thinking more of ideas. Those can be far more dangerous than any magic.”