AN ANCIENT SCIENTIST. 837 



On the other hand, Newton, perhaps the most exact thinker known 

 to scientific history, has expressed opinions on the constitution of mat- 

 ter closely resembling those of Lucretius. The latter asserts that all 

 substance consists of atoms, which are perfectly solid, and therefore 

 incapable of being crushed or torn apart ; for that which has no void 

 within itself can not be separated into parts : moreover, they are ex- 

 ceedingly hard, for otherwise they could not form hard bodies like 

 iron ; yet, when combined with " much void," they can give rise to 

 soft substances, as water and air. Compare this statement with Sir 

 Isaac Newton's belief, as expressed in the following terms : " It seems 

 probable that God, in the beginning, formed matter in solid, massy, 

 hard, impenetrable, movable particles of such size, figures, and with 

 such other properties, and in such proportion to space, as most con- 

 duced to the end for which he formed them ; and that these primi- 

 tive particles, being solid, are incomparably harder than any porous 

 body compounded of them even so very hard as never to wear, or 

 to break in pieces." If we except the belief in the creative power 

 of God, this quotation gives us Lucretius's atomic theory in a nut- 

 shell. 



Our author is again in harmony with the latest deductions of phys- 

 ics, when he asserts that the atoms have in themselves no sensible 

 properties, such as color, heat, etc. But the arguments which he uses 

 to establish this proposition are by no means convincing. His treat- 

 ment of the atomic motions, however, is the most vulnerable point in 

 his system. He supposed all constituted things to be produced by the 

 impact of atoms, which through all eternity were descending, urged 

 on by their own weight. Now, Lucretius had very clear ideas on the 

 subject of gravitation. He knew that, except when in a resisting 

 medium, all bodies fall with equal velocities. Hence, in this everlast- 

 ing, downward rain, it would be impossible for one atom to apjDroach 

 another and combine with it. To obviate this difiiculty, he conceived 

 a slight lateral motion, by which the particles are brought together. 

 He offers no reason for this extraordinary hypothesis, except that no 

 other supposition can explain the formation of things so as to accord 

 icith his theory. It is the old story of system first and facts after- 

 ward, and shows well the injurious tendency of the a priori method 

 in one who was otherwise well fitted for the pursuit of knowledge. 



Passing on to his other teachings, we find him devoting a whole 

 book to the bodily sensations. These, he attempts to show, are pro- 

 duced by corporeal images given off from bodies, and coming into con- 

 tact with our organs of sense. Thus, he thought that all things were 

 giving off thin pellicles of substance, which, by impinging upon the 

 eye, cause the sensation of sight. This is not unlike Newton's emis- 

 sion hypothesis. His theory of sound also is more purely mechanical 

 than that at present accepted. He supposes this sensation to be caused 

 by the direct passage of particles from the source of sound to the 



