As spirit can be descriptive so also emotion,
These words are part of our vocabulary defined and described from ancient times to allow us to understand in a spoken or written form physical reactions influencing and eminating from us.eg certain body language would denote fear or joy .the ancients through evolutionary language have brought us to the words like spirit or emotion and I'm sure many other words which share the same origins.
All made possible by the air we breath.
Photosynthesis is the culprit for better or worse. I'm sure most of us are grateful to that evolutionary process (tongue in cheek)!!!!