When natural philosophers in the seventeenth century encountered what they considered the endemic inscrutability of the world—below the threshold of sight, before the beginning of time, beyond the parameters of reason—their response was not always to suppose that better instruments, sounder logic, or more refined paradigms were the issue. Seventeenth-century thinkers believed in the generative role of the unknowable. Early modernity—its scientists, as much as its religious thinkers—was in part paralyzed by and in part energized by the gymnastics of paradox and contradiction in a "tradition" reaching back to Pseudo-Dionysius, Meister Eckhart, and also "popular," devotional mystics, such as Marguerite Porete or Margery Kempe, even while Protestant England often associated this tradition with enthusiasm, obscurity, and religious charlatanism.

Chapter 1 deals with the Book of Job, not so much the lamentable and put-upon Job, the figure who would come to be at the center of biblical theodicy, but rather the biblical book's detailed account of creation: Job's reputation for having a capacious scientific knowledge, and the simultaneous "fact" of his exemplifying cosmic ignorance. For early modern natural philosophy, the Book of Job was the chaotic and raucous twin of Genesis, and it represented an apophatic poetics of creation, things whose meaning and order could only ever be partially glimpsed. It was a book that perplexed and energized scientific writers—from Francis Bacon to Thomas Burnet and many more—and which provided a model for how natural philosophy might think through our human ignorance. Seventeenth-century thinkers found remarkable ways to put Job to work in their understanding of the origin of the world.

Jacob Boehme, a German shoemaker-mystic who wrote on the cusp of theology and philosophy in the 1620s, was translated and read voraciously in early modern England, and he became, for many radicals, the most important contemporary in an emergent "canon" of mysticism. Boehme's Mysterium Magnum (1623), a proto-Blakean account of a world, produces not so much a rounded philosophical system as a fugue of ideas, twisting and turning continually. However, his writing, by turns carnivalesque, poetic, and mystical—and which included a kaleidoscopic account of Genesis and the physics of Eternity—was also admired in philosophical circles. Few other writers so embody the dramatic nature of the unknowable, and how it produces its spiritual, scientific, and exegetical truths.

Sir Thomas Browne has long been thought to have a tinge of the mystic about him, even while, as a scientist, in his learned humanism and in his medical frame of reference he seems also to be from an altogether more sober world than the contemporary and enthusiastic mystic-radicals of civil war England, Holland, and Germany. However, in The Garden of Cyrus (1658), he writes on the edge of sanity. It is a text variously scientific, erudite, and scrupulous, yet demented and unfathomable, soaring toward its mystical finale, baffling readers with its puckish shape-shifting. By exploring its rhetorical style, the chapter makes the case that Browne's text mimics something essential about apophatic longing: its ravenous character, prone to inattention and never able to rest. In this, it can be understood in an apophatic lineage, connected to figures such as Pseudo-Dionysius, who address the character of the unknowable.

This chapter looks at early modern scientific encounters with the unknowable and the era's fascination with the minuscule—the vertigo of a micro-reality so counterintuitive and at odds with experience. It shows how natural philosophers in and around the Royal Society produced, in response to this, a poetics of distortion, a sometimes rhapsodic engagement with the strange and unpredictable worlds of microscopic science. Looking at Robert Boyle, Henry Power, Robert Hooke, and Walter Charleton, alongside Margaret Cavendish's scathing, haughty, and sometimes astute responses to them, the chapter argues that there is something fundamentally wrong in characterizing this set of debates as, primarily, an argument over the merits of the microscope as a technology. This was rarely more than a sideshow to fundamental questions about the character of the knowable and the unknowable in the mundane world.

Where medieval culture had its troublesome mystics, many of them women, early modernity had prophets, theatrical and bedlamesque, channeling unspeakable truths. Anna Trapnel's prophetic episodes in the 1650s were a phenomenon in which a self-educated, working-class woman, a Fifth Monarchist from a shipwright family, prophesied in Westminster, and grabbed the attention of London—its politicians and its religious radicals—across two weeks of tumult. Trapnel's truculent denunciations of Cromwell are, in one respect, a far cry from the "mystic tradition," but this seam of prophetic enthusiasm is nevertheless where mysticism went, a rhetoric not far from ranting that adopted the deranged style of biblical prophets, with their fragmented logic, as a correlate to a deranged world. Prophecy, indecorous and abrasive, aimed to awakne its listeners from their spiritual and political slumber, and addressed its attention to the eschatological and the eternal, as well as the mundane.

Milton's Paradise Lost is rendered with both a geometrical exactitude and a shape-shifting elasticity. This cosmogenic disorientation is theological in a quite different vein from the theology generally associated with the poem. In an epic describing the indescribable action of eternity, one of Milton's theological modes is akin to the apophatic, where the poem is suspended in the vertigo of its paradoxes, which will not resolve. Their contradictions are their theology. Against the idea that Milton is invested in the militant exercise of reason—the lesson that Adam and Eve fail to take sufficient note of—this chapter shows that the poem's incongruities, its dissonances and contradictions, are load-bearing facets of Milton's theology: we cannot reason our way beyond them. It situates Paradise Lost in relation to early modern ideas about the cosmology of the Book of Job and in relation to Jacob Boehme's depiction of the eternal.

The epilogue sums up the strange disciplinary connections that have been implicit across and between the chapters: that science and religion were tethered not only in their sense of a well-ordered creation, but also in their thoroughgoing nescience; that the radical political thought of the era not only owed a debt to mystical traditions and biblical prophets, but crafted a poetics, a language that reveled in its loss of coherence; and that the literary production of seventeenth century was indebted to an apophatic theology that grappled at the edge of what can and cannot be said. It considers also the haughty character of the apophatic, the fine-tuned social snobberies and venom of a mysticism keen not to be associated with ordinary bafflement, and demotic religiosity.