This paper delineates the early-modern re-conception of gender categories in the work of Margaret Cavendish, and her opposition of imagination and wit to the disenchanted reality produced by male thinkers of her time. Conceptions of “knowledge” and “truth” changed significantly during the first six decades of the seventeenth century, fashioning contemporary notions of masculinity and femininity. Against the background of the rise of modern science, within a system of epistemic hegemony synonymous with male strength and social superiority, Margaret Cavendish, Duchess of Newcastle, initiated a tacit work of feminine redemption by endorsing and elaborating conceptions imposed by the dominating habits of thought of her time. Responding to those philosophical discourses in which intellectual inquiry had taken on the traits of an allegorical penetration of the masculine “mind” into the secrets of a feminine nature, Cavendish reconceived that mind as the “Rational Soule,” understood as the source and objective of human knowledge. Cavendish forged an epistemological system which was intended not to oppose this “patriarchal” system, but to define a fanciful and witty dimension parallel to the masculine dominion of objectivity, where she manifested and realized the inalienable right for a woman to think within the intimacy of her mind and her house. The privacy of her “solitary mind” was not a prison but the independent locus of feminine cognition and enfranchisement.