 Though Astell discusses minds as if they are sometimes isolated from bodies, she maintains that human beings are mind–body unions. She notes that we cannot comprehend the connection between the mind and body: “We know and feel the Union between our Soul and Body, but who amongst us sees so clearly, as to find out with Certitude and Exactness, the secret ties which unite two such different Substances, or how they are able to act upon each other?” (Astell 2002, 148) The union between the mind and body is mysterious; though we “know and feel” it, we don’t have perfect knowledge of it or of how the mind and body interact causally. In Christian Religion, Astell presents this same position by way of a parallel between, on the one hand, our lack of knowledge of the mind–body union, and, on the other hand, our lack of knowledge about the relation between God and humans: “Again, tho’ I do not understand the Philosophy of the Union between the Divine and Human Nature; (neither do I comprehend the Vital Union between my Soul and Body, nor how and in what manner they are joyn’d, tho’ I am sure that so it is) …” (Astell 1705, 51 [section 62]).