As we come to the end of the century and the millennium, there is an irresistible temptation, especially for those of us who are old, to look back and try to assess the progress, if any, that has accrued. When I refer to scientific understanding, my aim is not to examine the understanding of science — i.e., how adequately people understand physics, psychology, biology, geology, etc. — but rather, to consider the kind of understanding that science furnishes to us. I shall focus on the understanding of the natural phenomena that scientific knowledge yields. In this endeavor, I want to emphasize the intellectual dimension of science, not the technology that has sprung from it, although I shall comment on the technological aspect toward the end.