This novel presents a remarkably modern—as well as post-modern—interrogation of the limits of religion, which is notable given the book’s medieval setting. From the outset, William embodies the philosopher Roger Bacon’s reliance on empiricism as a method of knowing. In the novel’s opening pages, he amazes the cellarer with his deductions about the abbot’s missing horse, and Adso is amazed as well. In his learned discussions with Severinus on the power of plants, we also see William’s faith in the “book of nature,” which can be read using reason and the powers of deduction.

When William and Nicholas discuss his eyeglasses, the glazier worries that people will fear such new technology. William confirms that this fear is real, and very, very dangerous. He admits that, when he was an inquisitor, he would never dare to use his eyeglasses while conducting interrogations because he might be branded a heretic along with his prisoner. He assures Nicholas that the “secretsof nature” are really “divine magic” (98), and should be embraced, not feared. But they both agree that sometimes knowledge that is gleaned empirically must be couched in religious language, in order to fool the simple people and to placate religious authorities.