Despite a surfeit of studies recognizing Cotton Mather's support for a range of alchemical and occult practices, historians have yet to integrate these occult activities with Mather's religious and scientific thought as a whole. I argue that we can bring clarity to Mather's engagement with the occult by refracting it through his reverence for Lutheran Pietist Johann Arndt, whose writings, especially Vier bucher vom wahren Christentum (Four Books of True Christianity), offer a key to Mather's employment of hermetic materials in his major works of natural philosophy. Through analysis of The Christian Philosopher and The Angel of Bethesda, as well as Mather's private writings, I suggest that Mather's cosmology was vitalistic in ways not previously acknowledged by historians. This view of creation as dynamic, enchanted, and marked by divine signatures—evidenced most clearly in Mather's concept of the nishmath-chajim—helped Mather reconcile the new science, Puritan covenant theology, and alchemical traditions descending from Paracelsus. By positing a divine, dynamic presence in nature, Mather retained an orthodox view of God as sovereign and transcendent while intimately engaged in a process of cosmic redemption, slowly transmuting the base matter of a fallen creation into a new heaven and new earth.