Until Charles Darwin's discovery of evolution, life was surveyed in the present tense. Animals were probed to see how their innards worked, plants dissected for useful magical potions, the creatures of the sea investigated for their strange lifestyles. Biology was about how living organisms thrived day to day.
Darwin forever transformed our understanding of life by insisting that life didn't make sense without the framework of its billion-year evolution. Darwin proved that even if all we wanted to know was how to cure dysentery in pigs, or how best to fertilize corn, or where to look for lobsters, we had to keep in mind the slow, but commanding dynamics of life's evolution over the very long term.
Until recently, economics was about how businesses thrived year to year, and what kind of governmental policy to institute in the next quarter. The dynamics of long-term growth are quite remote from the issues of whether the money supply should be tightened this year. The study of economics has no Darwin yet, but it is increasingly clear that the behavior of everyday markets cannot be truly understood without keeping in mind the slow, but commanding dynamics of long-term economic growth.