The experience of pleasure, alongside pain, is a primary element of human life.
It rules our instincts and desires for food, sex and avoiding various forms of harm.
Crucial to psychological and social well-being, it has preoccupied philosophers from Aristotle to John Stuart Mill and plays a fundamental role in moral and ethical theory, especially utilitarianism. More recently, it has become a central subject for psychologists, biologists and neuroscientists.