Emotion is both the source of most of our rationality, and a form of intuitive rationality.
Surprise/Fear is the rational statement-- there's danger there!
Anger-- There's injustice there!
Sadness-- This overwhelms me, I need to slow down
Joy... well, whatever.
Disgust-- That's unhealthy!
The only reason they aren't called rational is because they are instant responses, and balancing one with another helps us slow down to see if these responses are true or not.