P28: The ideas of the affections of the human Body, insofar as they are related only to the human Mind, are not clear and distinct, but confused.

Dem.: For the ideas of the affections of the human Body involve the nature of external bodies as much as that of the human Body (by P16), and must involve the nature not only of the human Body {NS: as a whole}, but also of its parts; for the affections are modes (by Post. 3) with which the parts of the human Body, and consequently the whole Body, are affected. But (by P24 and P25) adequate knowledge of external bodies and of the parts composing the human Body is in God/Nature, not insofar as he is considered to be affected with the human Mind, but insofar as he is considered to be affected with other ideas. Therefore, these ideas of the affections, insofar as they are related only to the human Mind, are like conclusions without premises, i.e. (as is known through itself), they are confused ideas, q.e.d.

Schol.: In the same way we can demonstrate that the idea that constitutes the nature of the human Mind is not, considered in itself alone, clear and distinct; we can also demonstrate the same of the idea of the human Mind and the ideas of the ideas of the human Body’s affections {viz. that are confused}, insofar as they are referred to the Mind alone. Anyone can easily see this.