What difference, if any, does the specific character of an individual's body make to the way that individual thinks, to his thoughts and to the sequence or association of his thoughts? What must the body be like, so that its contribution to thinking is reliable, and perhaps even useful? What nonepistemic benefits does the body bring to the mind? Although Descartes did not himself ask these questions in just these terms, answering them is central to the success of his enterprise. In any case, he provided the materials for addressing those issues, which he would have formulated as a problem about how divine epistemic benevolence - a guarantee of the possibility of demonstrative scientific knowledge - is expressed in the way that the body is structured, as it affects the mind.