202 SPECULATIVE SCIENCE 



in inventing the higher calculus of mathematics, and who 

 enounced the doctrine of vis viva. 



Adhesion, he thought, was obtained by motion, but how we 

 fail to understand. His explanation runs somewhat thus that 

 two bodies in motion, one after the other, are both trying to be 

 in the same place at once, and, as they cannot accomplish this, 

 stick together. Even Bernoulli, familiar with the views and 

 terms of the day, found Leibnitz's theory extremely difficult to 

 understand ; as found in his ' Hypothesis physica nova,' it is con- 

 tained in a series of short dogmatic sentences with very little 

 elucidation ; we may therefore be unjust to him in our ignorance, 

 but his criticism contained in his correspondence with Bernoulli 

 seems to us much more valuable than this blowing of little com- 

 plex bubbles. Thus he would not hear of the usual explanation 

 of solidity, by the supposition that particles were hooked to- 

 gether or entangled by their shape, as taught both by Lucretius 

 and Descartes. What, he asks, is to keep the hook together ? 

 and he got no answer. He refused to admit Lucretius's pos- 

 tulate of infinitely hard bodies and infinitely elastic bodies ; 

 indeed, the two properties do seem incompatible. The elas- 

 ticity which we observe is given by a change of position of the 

 parts of the body, and if the parts never change position it is 

 hard to see by what the energy required for elasticity can be 

 represented. He further objected to the assumption that atoms 

 were indivisible, since, however small we conceive a particle to 

 be, we can invariably think of its parts. Leibnitz was not to be 

 satisfied with the idea which Lucretius seems to hold, that a 

 thing may exist just big enough to have parts too small in 

 themselves for independent existence. John Bernoulli, however, 

 did not quite abandon atoms in consequence of this attack ; like 

 a sensible man he does not like assumptions of infinite hardness 

 and infinite elasticity, but he replies to Leibnitz that atoms may 

 be so constituted that they may be really indivisible by any 

 process to which they can be subjected by other atoms, although 

 they may have an infinity of parts such as the mind can 

 conceive. 



We will now endeavour to trace the development of the 

 school which, discarding the hard solid elastic atoms of Lucre- 

 tius, attempts to deduce the properties of matter from the 



