Among the many advantages enjoyed by the present generation, one of the most conspicuous is that arising from the large advance made in physical science. The high value of this is apparent from whatever standpoint it is regarded. The vastly wider range of knowledge, the increase of appliances for inquiry, the greater facilities for work of all kinds, the freer intercommunion of all the divisions of our race, and the greater altitude from which the whole realm of existence can be contemplated; all these involve an immense gain for the present century. With these advantages, however, there comes the difficulty of using them aright, a difficulty which we may expect to be greater when we are dealing with wider and more general aspects of existence, than when we are concerned with more restricted ranges of knowledge. It may be a much easier thing to state precisely how recent advances have affected a particular branch of science, such as astronomy or geology, than to say how they bear upon the general conception of the universe. Yet, while the latter is the more difficult question, it is that with which men generally must be more concerned. Only a very limited number of men can belong to the ranks of specialists devoted to a single branch of science. All men, specialists as well as others, are concerned with the wider question as to the true conception of the universe, and the bearing it has on human life and destiny. It is impossible to imagine that marked advance can be made in any of the sciences, without its having some bearing on the more general problem in which all men are practically interested. Each specialist perceives this more or less clearly as he is working out the result of complicated observations or calculations. The public mind may be said rather to _feel_ that some modification of common belief is taking place, while there is great uncertainty as to the actual change. What gives a sense of security to the general conviction of educated men is that all increase of knowledge is clear gain, and that all advance is secured on familiar and well-tried lines. Progress is transition, and in a sense unsettling; but it is also accumulation, and thus in a more enduring sense, consolidating. Fresh observation in some one department of research does not overthrow all that was credited previously. It extends the area of knowledge, or carries us into a more minute acquaintance with particulars, and only in a restricted way modifies accepted positions, by introducing relations formerly unrecognized. Thus, progress in a particular science does not unsettle scientific belief.