SCIENCE, and the humanities. How often are they placed in opposition. There is doubtless a utilitarian aspect of science which though admirable in itself tends to foster a spirit antagonistic to culture. But science is many-sided. And in the single-minded seeking for the truth amidst clouding obscurities, in the searching out the laws of the development be it of an atom, a tree, a man or a star, in the aim to express that unity which we instinctively feel is the key to the interpretation of nature's marvelous complex, I feel that she earns an honored seat among the immortals. And so I need make no apology for speaking to you upon a scientific subject, one which lies at the very basis of natural science, one whose development has demanded not only zealous, strenuous research but calm judicial, wise speculation,—the subject of the constitution of matter, the stuff of which the physical world is made.
The ultimate structure of the material world around us must always have been a problem of deep interest to thoughtful minds, and has formed a fruitful subject of speculation from the time of Thales to the present day. But it is not of the philosophical aspect of the question that I venture to speak. I can not claim to be a philosopher—save such a one as is characterized by Touchstone as a "natural philosopher"—but only a student of physics; and it is therefore to the physical side of the problem that I shall confine myself. The substance and the form of Aristotle, the monad of Leibnitz, the strife between idea and thing-in-itself, and other metaphysical contributions toward the interpretation of the universe, important though they be in the history of thought, are beyond the limitations of the present speaker and of the present occasion. Our attention is rather to be directed to the physical theories which have been framed as to the constitution of matter, especially to the one which has won almost universal acceptance, that known as the atomic theory; its development from the past, its modern form, and its promise for the future.
For the hypothesis of atoms is not a product of modern science. Indeed the question of the divisibility of matter must necessarily arise in the early stages of scientific thought. In our youth when we inquire as to the structure of things we are told that
Little drops of water,
Little grains of sand,
- Address delivered before the joint meeting of Phi Beta Kappa and Sigma Xi, University of Pennsylvania, June 16, 1909.