We know that there are two frontiers in the study of the basic laws of natural science: the frontier of the very large, the cosmos, and the frontier of the very small, the structure of the elementary particles out of which the entire universe is constructed, including us. The combination of these two (at the present time theoretically unrelated, although we hope that this situation won't persist) gives us the basic scientific laws that form the foundations for our discussions of science. The research in both of these fields is necessarily a close partnership of theory and observation, and the availability of numerous experiments in the study of the very small is what has made progress in that field more rapid and more exciting in recent years than progress at the other end. But, as interesting observations of the cosmos accumulate, cosmology too should flourish. One thing that makes the adventure of working in our field particularly rewarding, especially in attempting to improve the theory, is that at this basic level of science a chief criterion for the selection of a correct hypothesis, even more than elsewhere in science, seems to be the criterion of beauty, simplicity, or elegance.