With his 1620 Novum Organum, the forefather of modern science, Francis Bacon, developed a distinctive philosophic orientation to non-human nature that perceived man as a "modest witness"—both separate from and dominant over the material world. Having recognized this historical context, the Introduction presents a significant feminist Enlightenment tradition that not only critiques such masculine modesty but also offers an alternative to it. Drawing on materialist philosophies, this tradition embodies an alternative history of sublime knowledge-making enabled by the practice of sensitive witnessing, which prioritized knowledge gained through embodied observation that defied separation between scientist and specimen. Contrary to conventional understanding, intermingling with matter was a key dimension of early modern philosophers' empirical practice. The Introduction asserts that various British female philosophers of the Enlightenment era used this often underplayed dimension of the new science to claim access to philosophical authority.

Chapter One explores how Lucy Hutchinson and Margaret Cavendish develop a practice of sensitive witnessing from opposite sides of the political spectrum that, directly influenced by Lucretian Epicureanism, sets an important foundation for transforming one's association with matter, as a woman, from an encumbrance into an asset. Insisting that all beings (whether male or female) are prone to the pull of and identification with matter, these author-philosophers challenged Bacon's investment in the modest witness. They instead promote an empirical practice that values the physical and psychological intimacy facilitated by atoms and that uses such intimacy for philosophical discovery and insight. For both Hutchinson and Cavendish it is the empiricist who cultivates rather than eschews softness—openness, vulnerability, sensitivity—that has the potential to restore a "rusty" age and is therefore well prepared to enact a truly "great instauration."

Chapter Two explores how Behn drew significant inspiration from Lucretius's De Rerum Natura. It asserts that Behn presents a strong critique of contemporary philosophical practice while proposing an alternative that is distinguished by libertine Epicureanism. Behn encourages her readers to appreciate how sensory stimuli move and beguile our will, making us profoundly vulnerable to our environments. While such vulnerability threatens Baconian empiricism, which is invested in masculine modesty, it proves to be a boon to the philosophical practice that Behn models and promotes. It enables discoveries and insights that are unavailable to the masculine modest witness and, in so doing, shows that femininity is something to be proud of as a philosopher. Behn parodies masculine philosophical modesty and, in so doing, sets a foundation for the appreciation of feminine sensitive witnessing.

Chapter Three argues that Haywood presents a sensitive witness who is distinguished by skeptical doubt. Philosophers should, according to Haywood, practice sensitivity so that they may maximize their access to empirical truths. However, as they do so, they should take care to avoid becoming dogmatic or overly attached to a certain result of their enquiries. They must remain steadfast and thus resilient in the face of whatever truths come their way. Haywood advocates a philosophical method of sublime knowledge-making that is informed by a feminist practice of sensitive witnessing. However, acknowledging the challenges that sensitivity can pose to philosophy, particularly when it manifests as desire, Haywood introduces radical skepticism into her method, suggesting that it has the capacity to protect philosophers from the temptation to allow their sensitivity and desire to metamorphose into attachment, zealotry, enthusiasm, dogmatism, and even obsession.

Chapter Four shows how, at the end of the Enlightenment era, Charlotte Smith preserved the philosophical value of sensitive witnessing even as it became associated with the "cult of sensibility," which had become a target of satire by the end of the eighteenth century. For Smith, the sensitive witness must combine feeling and reason. In doing so, they not only avoid the superficiality that was regularly seen to characterize sensibility but also cultivate an ontology of kinship and an ethic of care, which are, according to Smith, valuable to both philosophy and the public good. Smith harnesses the popularity and power of sensibility for the sake of poetry and philosophy while distinguishing it from itsmore conventional expressions that tended to result in self-indulgence as well as cliché. The sensitive witness is, for Smith, not simply of value to the collective pursuit of knowledge but also to social justice.

Feminist "new materialism" has a deep, albeit often unrecognized, history that stretches back to the Enlightenment era. Whereas male philosophers of this era regularly insisted on a fundamental distinction between active man and inert matter, contemporaneous sensitive witnesses instead celebrated their entanglement with the material world. Moreover, they insisted on bearing witness to the vitality of matter while rejecting the binarisms that help substantiate the modern self's opposition to nature. Thus, Enlightenment era practices of sensitive witnessing set an important foundation for twenty-first-century material feminisms. From them, we may learn that, to become capable of caring for the material world, we must 1) develop a more capacious perception of ourselves that includes rather than excludes others, both human and non-human, and 2) appreciate knowledge-making as a sublime endeavor that is predicated not on distance but, rather, on physical and emotional intimacy.