THE CONSTITUTION OF MATTER. 3 



We DOW know that matter is not indefinitely divisible, 

 and that the smallest parts of the various simple substances 

 existing in those that are naturally compound have not all 

 the same dimensions, nor equal weights. Chemistry, by a 

 course of analyses and measurements, has succeeded in de- 

 termining the weights of atoms of the different elements, 

 that is to say, taking as a unit an atom of the lightest ele- 

 ment, hydrogen, in determining the weight of the atoms 

 which are equivalent to this conventional unit in the various 

 combinations. Though many savants continue to maintain 

 that atomic weights are nothing but relations, and that 

 the existence of atoms is a mere logical device, it seems 

 more reasonable to admit, with the majority of those who 

 have studied this difficult problem closely, that these atoms 

 are actual realities, while it may be very far from easy to 

 settle precisely their absolute dimensions. In any case, we 

 may affirm that these dimensions are very much less than 

 those presented by the particles of matter subjected to the 

 most powerful and subtile methods of division, or decom- 

 posed by the imagination into its minutest elements. " Let 

 man," says Pascal, " investigate the smallest things of all 

 he knows ; let this dot of an insect, for instance, exhibit to 

 him in its diminutive body parts incomparably more dimin- 

 utive, jointed limbs, veins in those limbs, blood in those 

 veins, in that blood humors, and drops within those humors 

 let him, still subdividing these finest points, exhaust his 

 power of conception, and let the minutest object his fancy 

 can shape be that one of which we are now speaking he 

 may, perhaps, suppose that to be the extreme of minute- 

 ness in Nature. I will make him discover yet a new abyss 

 within it. I will draw for him not merely the visible uni- 

 verse but all besides that his imagination can grasp, the 

 immensity of Nature, within the confines of that impercep- 

 tible atom." In this Pascal displays a feeling as true as it 

 is deep of the infinitely small, and it is interesting to ob- 



