  One interesting element of what could be characterized as her admiration of Descartes' method is that the Foundations fairly closely tracks the structure of Descartes' project in his Principles of Philosophy. Both texts start with indubitable principles of knowledge, which, in the first instance, lead to conclusions about the metaphysics of God. These conclusions allow one to gain knowledge of the metaphysical structure of the world, which in turn grounds physical laws that allow the observer to make scientific sense of the world (Lascano 2011, 742–3; c.f. Zinsser 2006, 173). This underscores at least that the two thinkers had a shared interest in developing a unified natural philosophy with a well-worked out, and fairly robust, metaphysics detailed first. Another highly plausible reading of Du Châtelet's mimicking of Descartes' mature work is that she sees herself offering a new natural philosophy to replace the largely rejected Cartesian system, just as Descartes before her aimed to replace the old Scholastic natural philosophy with his Principles of Philosophy. This interpretation is born out by a comparison of the two texts, for there are important divergences between them, not just on the details in the metaphysics, but also on the range of topics addressed. For Descartes' forays into what we would now call “science” included not only astronomy and physics, but planned sections on living bodies and on the human being, including its soul, thus promising to touch on topics such as human health and morals (in keeping with his metaphor of the tree of philosophy offered in the preface to the Principles). In contrast, Du Châtelet's text deals exclusively with physics, leaving the broader array of natural philosophical topics and moral philosophy left untouched. Still, the overall similarity in structure between the two texts indicates her affinity, at least with respect to her overall project, with Descartes. Here, we examine a few crucial moments in her Foundations, underscoring how she and Descartes compare and contrast on these points, with an eye to showing some central aspects of her own brand of natural philosophy, and some of the ways in which Du Châtelet fit (and did not fit) into the French Enlightenment (especially with regard to Newtonianism and scientific methodology).