When Eileen O'Neill (1953-2017) published her ground-breaking essay, "Disappearing Ink: Early Modern Women Philosophers and the History of Philosophy" in 1998, women philosophers were virtually absent from encyclopedias of philosophy and the numerous histories and anthologies of early modern thought. This essay would come to have an enormous impact, signaling the beginning of the movement to introduce early modern women philosophers into the canon. In its densely-packed 46 pages, "Disappearing Ink" presented the names, major works, and principal theses of literally dozens of forgotten women, whose works were published during the early modern period and who had engaged in correspondence with central male figures but whose names and works had since been erased. Disappearing Ink reprints this now-canonical piece together with subsequent essays, some widely read, some harder to locate, and one, on "Cartesianism and the Gendered Mind", written in 2013 and published here for the first time. The essays in Part I develop O'Neill's views on feminist history of philosophy, articulating an account of feminist historiography that is inclusive yet at the same time textually nuanced. The essays in Part II provide in-depth treatment of individual figures and themes. These essays discuss the views of early modern women philosophers such as Mary Astell, Margaret Cavendish, and Mme de Lambert alongside those of Descartes, Leibniz, Poullain de la Barre, and the Scholastics, engaging with questions of mind-body interaction, occasional causation, physical influx, pan-organicism, and whether the Cartesian mind is gendered. The sole essay in Part III departs from the historical orientation of Parts I and II. This essay, informed by O'Neill's deep knowledge of art history, is an illuminating study of agency in representations of women in feminist erotic art of the 1980s. Combined, these works trace the complete arc of O'Neill's thought, from painstaking studies of individual themes and figures to a sweeping vision of how feminism should inform our approach to the history of early modern thought--indeed, to the history of philosophy more generally. More than anyone else, O'Neill explained why women were excluded from the canon and showed how they could be incorporated into it.