SCIENCE AS A SYMBOL AND A LAW 9 



action, but even denies them the power of deciding 

 qualitatively between phenomena; for the light which 

 affects the eye, the sound heard by the ear, and the heat 

 perceived by temperature are essentially the same thing, 

 mere variations of a universal force of gravitation. 

 These different attributes of matter are scientifically 

 identical if the forces involved are equal; for as force, 

 however manifested, was held to be a mechanical at- 

 traction between atoms, all these quantities can be 

 weighed in a chemical balance and have no essential 

 difference. While there may have been great diver- 

 sity amongst the physicists of the last century as to de- 

 tails, there was but this one explanation of nature: 

 The universe was a complicated machine, whose visible 

 parts were connected together by a system of intangible 

 links called atoms, whose complex motions, while they 

 might defy our analytical skill, were yet completely 

 expressible by general mechanical laws. 



To find the weak spot in this mechanistic theory, 

 based on the hypothesis of the atom, is not only a dif- 

 ficult task, but is one which ran so counter to the 

 accepted teachings of science and to the natural preju- 

 dices of the mind, that it is not strange if most men 

 of science now reason as though the atom were a 

 matter of experimental proof rather than of metaphys- 

 ical speculation. Such a mechanistic theory of natural 

 law as Lagrange and Laplace evolved, and as scientific 

 thought of the last century extended, must necessarily 



