Books are never harmless...they either strengthen us or they weaken us in our faith. Some of them do this even as they entertain us, others as they teach us. In an invisible way their teaching penetrates into our hearts and souls, to continue its work inside, and we inhale the spirit of these books as healing or poisonous vapors. They can bring the greatest benefits and the greatest ruin, for from their ideas that they spread come the deeds of the future.