Similar to how practitioners of other faiths will appeal to passages in their sacred texts to justify their beliefs or actions, adherents of many Pagan traditions will often appeal to natural phenomena, science, personal experience, or (the closest thing to sacred scripture) mythology. For example, nearly all Pagans reject the idea of belief in a single, masculine deity, by pointing to the simple fact that nearly all animals include two genders, male and female, which would then necessitate that God (or the gods) could never be limited to just one sex.
"Reading" nature (or science or personal experience), therefore, is a tool for cultivating one's own individual spiritual wisdom, similar to how adherents of other faiths will read their sacred texts for inspiration.
Carl McColman is an independent scholar and freelance writer. His areas of study include Christian and western mysticism, Celtic spirituality, and Neopaganism. He received a Master of Arts degree from George Mason University in Professional Writing and Editing. His books include The Complete Idiot's Guide to Paganism (Alpha Books, 2002), The Complete Idiot's Guide to Celtic Wisdom (Alpha Books, 2003), When Someone You Love is Wiccan (New Page Books, 2003), and Spirituality: A Postmodern and Interfaith Approach to Cultivating a Relationship with God (White River Press, 2008).