emotions have helped us survive

When we lived in the wild we needed emotions in order to react quickly to dangerous stimuli. We developed an emotional system because it could induce quick responses to danger.

We developed basic emotions (fear, joy) like the other animals. But then we developed a more complex rational system too, in which we could imagine our own past and future selves.

We now have two highly developed systems: reason and the emotional core still sitting there, like the primitive animal inside us. As said above, mental illnesses often result from an imbalance in those two.

The wise mind puts emotion and reason in conversation, or uses reason to calm emotion down.