The popular idea that chemistry is now conceptually understood and that all we have to do is use it is false. Sure, most of the products we use in our daily lives were made possible by modern chemistry. But producing useful compounds is far from all chemists do. In fact, many of the most pressing problems of modernity—from making cars cleaner to altering the fate of living cells—are, at heart, problems in chemistry and will require chemists to solve them. So, too, will some of the most fundamental mysteries in science.