The Book of Nature

The book of nature is a longstanding Christian metaphor holding that God has revealed himself through two distinct books, scripture, God's revealed word, and nature, God's created work, and that because both books share the same divine author, rightly read they cannot ultimately contradict one another, a principle that gave many pre-modern and early modern Christian thinkers grounds for pursuing natural philosophy, the historical ancestor of modern science, as a genuinely religious as well as intellectual undertaking. The metaphor has roots reaching back to patristic writers including Augustine, who described creation itself as a kind of book available to be read even by the illiterate, and it received one of its most consequential applications when Galileo Galilei invoked the two books principle directly in his 1615 Letter to the Grand Duchess Christina, arguing that apparent conflicts between the literal text of scripture and the findings of natural philosophy should be resolved by recognizing that scripture is written to accommodate ordinary human understanding on matters of salvation, while nature, correctly investigated, speaks with its own unmediated and equally divine authority on matters of physical fact.

A structurally comparable idea appears independently in Islamic thought, where the Quran uses the word ayat, signs, for both its own individual verses and for the phenomena of the natural world, the sun, the alternation of night and day, the diversity of languages and colors, each described as a sign pointing toward God for those who reflect, a linguistic and theological convergence of scriptural and natural revelation under one shared term that gave medieval Islamic natural philosophy, like its Christian counterpart, religious grounds for the empirical study of nature.

The book of nature metaphor functioned historically as a companion to natural theology rather than as identical to it, since natural theology names the philosophical project of arguing from nature to conclusions about God, while the book of nature is more precisely the theological premise, that nature is itself a form of divine communication continuous with scripture, that made such a project seem religiously legitimate rather than a distraction from revealed truth in the first place. The metaphor's influence waned as natural science professionalized and increasingly separated itself methodologically from theological framing from the eighteenth century onward, though it continues to be invoked, particularly in Catholic and some Protestant theological writing on science, as a historical and continuing warrant for treating scientific inquiry as compatible with, rather than opposed to, religious faith.