Long ignored by psychologists, who have concentrated on more easily measurable processes like memory and learning, the emotions remain a mystery.
But as the evidence continues to mount about the power they have over us, social scientists are now finally focussing on feelings.In the first of this series, Claudia Hammond bravely ventures into the unknown, exploring what's believed to be the first emotion, 500 million years old, but as potent today as it ever was.
Listen, if you dare, to Fear!.
From Basil Fawlty to trolley rage, Claudia Hammond investigates the most violent emotion, and asks whether we're angrier today than ever before.
It's the emotion that has you squirming in your seat and wishing you could re-write history.
But without it, could we trust anyone? Is it the glue that sticks society together? Claudia Hammond investigates guilt and its close relative, shame - and discovers that feeling guilty can even affect your immune system.
The fourth programme examines sadness.
The fifth programme examines jealousy.
Claudia Hammond proves that she has a strong stomach as she examines the emotion with the yuck factor: disgust.
It seems that the reason for squeamishness could be to protect us from disease.
Claudia Hammond discovers that simply imagining oneself laughing can bring all the benefits associated with happiness when she asks why and when we feel joy.
Claudia Hammond hears that empathy, while it may be a buzz word on team-building courses, is actually an inferior version of the more moral emotion, sympathy.
Claudia Hammond turns the spotlight on the emotion we're all addicted to: love and discovers that everything's far from coming up roses.
Claudia Hammond ends the series on an optimistic note with a look at hope, the emotion that's essential if we're to keep going.