The human mind is the idea of the human body
Formal Statement
The object of the idea constituting the human mind is the body — a certain actually existing mode of extension, and nothing else. The mind is not a free-floating soul; it is the idea of this particular living body.
In Plain Language
Your mind is not some ghost piloting a machine. It is the mental side of your body's ongoing life. Every ache, heartbeat, and gesture has a corresponding thought — not because the body "sends signals" to the mind, but because the mind just is the body understood from the inside. Emotion, then, will never be purely mental; it is always also something your body is doing.
Why This Follows
Given the parallelism of ce-01, every mode of extension has a corresponding idea in God. Spinoza shows that the idea that constitutes your mind corresponds precisely to your body as its object, since we plainly possess ideas of the body's modifications (II, Axiom IV).
Emotion is always embodied — the mind feels what the body undergoes because the mind is the idea of the body.
If the mind is the idea of the body, could a radically different body (say, an octopus body) have a radically different kind of mind?