22 THE LIMITATIONS OF SCIENCE 



preventing the adoption of the temporarily more con- 

 venient wave theory. 



Whether or not it is advisable to substitute energy 

 for inertia, or mass, as the general attribute of matter 

 which will best serve for a fundamental unit, may be 

 open to discussion. But it seems certain to me, at 

 least, that the formulation of laws deduced mathe- 

 matically from experimental data alone, and not con- 

 jecture as to the causes of phenomena, is the true 

 province of science and the only method certain not to 

 lead us into vain metaphysical speculation. 



Unfortunately, the restraint and clarity of thought 

 shown by Rankine are rare, and few are willing to 

 impose limitations on speculation or to forego the at- 

 tempt to create a subjective and metaphysical scheme 

 according to which nature shall work. In the hands 

 of his successors, notably Mach, Duhem, and Ostwald, 

 these barriers were cleared. They have endeavored to 

 give an objective reality to the mathematical equation 

 of energy. To make an entity of a symbol, to speak 

 of centers of force as if an intelligible image were 

 conveyed to the mind, to make matter and inertia an 

 attribute of energy, is even more metaphysical than 

 the concepts of atoms and ethers, which could, at least, 

 be likened to sensible objects. With Professor Ost- 

 wald, the most militant defender of the science of 

 energetics, matter disappears altogether; empty space 

 is known to us only by the quantity of energy necessary 



