What are things made of ? 'Everything is composed of small mollycules of itself, and they are flying around in concentric circles and arcs and segments', explains Sergeant Fottrell in Flann O'Brien's The Dalkey Archive. Philip Ball shows that the world of the molecule is indeed a dynamic place. Using the chemistry of life as a springboard, he provides a new perspective on modern chemical science as a whole. Living cells are full of molecules in motion, communication, cooperation, and competition. Molecular scientists are now starting to capture the same dynamism in synthetic molecular systems, promising to reinvent chemistry as the central creative science of the new century.