The period from the late fourth to the late second century B. C. witnessed, in Greek-speaking countries, an explosion of objective knowledge about the external world. Yet, not long after this golden period, much of this extraordinary dev- opment had been reversed. Rome borrowed what it was capable of from the Greeks and kept it for a little while yet, but created very little science of its own. Europe was soon smothered in theobscurantism and stasis that blocked most avenues of intellectual development for a thousand years — until, as is well known, the rediscovery of ancient culture in its fullness paved the way to the modern age.