It's a fine book and very deeply rooted in magic, as you'd expect! The point about sacrifice is true, but that doesn't mean it has to be a blood sacrifice. The gods of nature require material offerings: incense, pure water, and wheaten cakes were standard practice among the old Neoplatonists. (Compare that to traditional Shinto offerings, especially those made to the kunitsu no kami, the kami of earth, and you'll notice some very interesting similarities.)