Any one who has glanced at the development of science from old times up to the present is well aware of that weakness in the mind of scientists—especially the non-pioneer scientists—which induces them to believe that the conclusions they have arrived at, generally in opposition to predecessors, are the whole truth and nothing but the truth. For thousands of years it has been the same. For each step that science has climbed upwards, its votaries, with a few brilliant exceptions, have believed themselves to be at the top, and have with scorn rejected, as sheer folly, any suggestion that the step on which they stand is rotten and that there are sounder steps higher up. The scientists of other days in their turn looked upon Columbus, Galileo, and Tycho Brahe as fools. A hundred years ago the scientists would have laughed to scorn any one who had told them that their senses deceived them with regard to light, darkness, colours, silence and sound, and that all these presentations received by our senses were simply movement or manifestations of energy. The theory which regarded atoms as minute subdivisions of matter is quite a modern dogma, and yet it is already tottering to its fall. More rational scientists already speak of atoms as centres of force, an expression which twenty years ago was regarded as rank heresy. If the theory that atoms are centres of force is accepted, with all its consequences, science is on the threshold of a new departure which may cause the materialists to look small indeed; for if what to our senses appears as matter is a condition of force, instead of force being a condition of matter, a vista entirely opposite to that of the materialists is open to science—a vista disclosing possibilities before which we might well stand in awe.