It follows that spillover – the fact that others pinch your ideas – is not an accidental and tiresome drawback for the inventor. It is the whole point of the exercise. By spilling over, an innovation meets other innovations and mates with them. The history of the modern world is a history of ideas meeting, mixing, mating and mutating. And the reason that economic growth has accelerated so in the past two centuries is down to the fact that ideas have been mixing more than ever before.
