The fiftieth anniversary of the death of Camille Flammarion, the great French astronomer, is the occasion for the authors of this article to review the beginnings of modern science writing. Flammarion's Popular Astronomy may be considered the first step in the popularization of science. The relation of science communication to other disciplines is discussed as well as the contemporary approach. One of the tasks of the popularizer is to present a correct image of science to the public. The authors conclude with a statement of UNESCO's involvement in the popularization of science.