P1: In just the same way as thoughts and ideas of things are ordered and connected in the Mind, so the affections of the body, or images of things are ordered and connected in the body.

Dem.: The order and connection of ideas is the same as the order and connection of things (by IIP7), and vice versa, the order and connection of things is the same as the order and connection of ideas (by IIP6 C and P7). So just as the order and connection of ideas happens in the Mind according to the order and connection of affections of the Body (by IIP18), so vice versa (by IIIP2), the order and connection of affections of the Body happens as thoughts and ideas of things are ordered and connected in the Mind, q.e.d.