Our noses can give us even more information than our eyes and ears, suggests Harold McGee, who takes a sensory adventure from the sulfurous earth of more than four billion years ago, to the fruit-filled Tian Shan mountain range north of the Himalayas, to the keyboard of your laptop, where trace notes of phenol and formaldehyde escape between the keys. Through it all, McGee familiarizes us with the actual bits of matter that we breathe in—the molecules that trigger our perceptions, creating the citrusy smells of coriander and beer and the medicinal smells of daffodils and sea urchins.