For animals, unburdened by the need to translate physical sensations into abstract language, emotions function smoothly, as they were meant to. For us, the split between our emotions and our cognition is a source of constant internal friction, comprising a second Emotional Self within us that operates beyond our will. Animals feel fear for a brief time, then it is gone. We dwell on our fears, intensifying them and making them last well past the moment of danger, even to the point of feeling constant anxiety.
From The Laws of Human Nature by Robert Greene