Theophanic Reasoning: Science, Secrets, and the Stars from Spenser to Milton posits that early modern English literary figures use the concept of theophany, the material or transferred presence of God in the terrestrial world, to respond to the vacuum of doubt instigated after Nicolaus Copernicus published his astronomical observations in 1543. From heretical theories of the world-soul expressed through pagan Roman myth in Spenserian epic and Shakespearean drama, to the deeply spiritual and lively negotiation between man and the divine in Francis Bacon’s scientific writings and John Milton’s Paradise Lost, Theophanic Reasoning argues that Protestant writers use theophany as a cipher to reason, or rationalize, the anxiety accompanying the scientific method, which threatened to eliminate God the Maker from the universe entirely. As a literary history of religion and science, Theophanic Reasoning makes a critical intervention between religious studies and the history of science. In doing so, it argues that seventeenth-century literature acts as the gravitational force that pulls these now-disparate fields into cooperating orbits. Whereas current literary scholarship focuses on the history of science or the “religious turn” as separately evolving critical conversations, this dissertation returns to the original historical milieu of the seventeenth century by forging careful analysis of historical materials and Latin philosophical texts with recent research in Christian mystical theology and the esoteric branch of the history of science discipline. Thus, Theophanic Reasoning addresses a crucial gap in scholarship between literature and religion and literature and the long history of science. At the heart of this project is the early modern brokering between the ontological status of truth and lies, belief and proof. It argues that Protestant believers used verifiable proof of God’s presence—in the cosmos, in the atmosphere, on the human body—to explain and further buoy scientific experiment and reality. It seeks to answer the question of what happens to literature when two giant cultural shifts, the Protestant Reformation and the Cosmological Revolution, threaten to rend the very fabric of religious and intellectual life in England. With particular attention to early modern understandings of facticity and sensory experience, Theophanic Reasoning provides a religio-scientific reading practice to redefine the secularizing impulse of contemporary literary criticism. In turn, this dissertation seeks to restore the divine to its place in early modern conceptions of science, secrets, and the stars.