"Metaphorical thinking—our instinct not just for describing but for comprehending one thing in terms of another—shapes our view of the world, and is essential to how we communicate, learn, discover and invent. ... Our understanding of metaphor is in the midst of a metamorphosis. For centuries, metaphor has been seen as a kind of cognitive frill, a pleasant but essentially useless embellishment to 'normal' thought. Now, the frill is gone. New research in the social and cognitive sciences makes it increasingly plain that metaphorical thinking influences our attitudes, beliefs, and actions in surprising, hidden, and often oddball ways."
Geary further unpacks metaphor's influence in his foreword:
"Metaphor conditions our interpretations of the stock market and, through advertising, it surreptitiously infiltrates our purchasing decisions. In the mouths of politicians, metaphor subtly nudges public opinion; in the minds of businesspeople, it spurs creativity and innovation. In science, metaphor is the preferred nomenclature for new theories and new discoveries; in psychology, it is the natural language of human relationships and emotions."