Beware of the troll

Beware of the troll. Trust him not. Turn him from your door. He is nothing, a mere accident of forces, unwritten, unclean, the mineral world’s pale, jealous echo of living, thinking creatures. In his head, a rock; in his heart a stone. He does not build, he does not delve, he neither plants nor harvests.

(Mr. Shine. Him diamond!)

Terry Pratchett, Thud!