The source of our emotions remains elusive. No one knows exactly where emotions
come from, what makes us feel the way we do, or whether we can fully control the way we
feel. Emotion is intimately related to cognition and culture, and it affects us
physically: our bodies react to different emotional states, and we often show emotion
physically. Researchers have proposed many theories about the source, purpose, and
expression of emotion.
In many ways, our emotions define our existence—without them, most of us would not
feel truly alive. We’ve all felt fear of a lurking stranger, pride at scoring well on a
test, love, sadness, and loneliness. And between emotional extremes are the ups and
downs of everyday life: frustration in a traffic jam, contentment over a satisfying
lunch, amusement at a cartoon. We have much to learn about emotion—but we have also
learned simply by being human and feeling things every day.