836 THE POPULAR SCIENCE MONTHLY. 



the other senses, but not that of sight. This is proved by the sensa- 

 tions of sound, heat, and smell, which must be produced by matter, 

 for to give rise to the feeling of touch is the essential property of 

 matter and of matter alone. This property is what he calls an offi- 

 ciwn corporis that is, a " function of substance " ; another which he 

 mentions afterward is weight, or the tendency to proceed downward. 

 He also demonstrates the presence of aqueous vapor in the air by the 

 phenomena of absorption and evaporation. A quotation of his lan- 

 guage at this point will give a fair idea of his logic and his style : 

 " In short, garments hung on the surf -beaten shore grow moist, but if 

 spread out in the sun they become dry again. Yet we have not seen 

 how the moisture of the water made its way in, nor how it vanished 

 beneath the heat. The water, then, is scattered into minute parts, 

 which the eyes can in no way behold." He employs arguments that 

 are in use nowadays in physics to prove the smallness to which matter 

 can be subdivided. The most solid bodies, such as rings upon the 

 fingers and the very stones beneath our feet, are worn away by con- 

 stant rubbing. " But," as he goes on to say, " the nature of sight 

 has enviously shut off the view of those portions of the substance 

 which disappear at any one time." 



The arguments which he uses in this connection form an additional 

 proof of the scientific tendency of Lucretius's mind. In his time the 

 inductive and experimental methods were imperfectly understood and 

 little practiced. He himself does not appear to have attained to them, 

 he was bound by the false philosophical notions of the Greeks ; yet 

 often, as here, he traces the cause from various effects with consider- 

 able sagacity. He has in several cases, though generally on insufiicient 

 evidence, anticipated some of the results of modern research. It is 

 easy to see how his opinions would have been strengthened, and what 

 added breadth and vigor of reasoning he would have gained, if he had 

 stood on our vantacre-ffround and had known all that we now know. 

 As it is, we feel surprised at finding that he accomplished so much 

 with such imperfect material for his work. 



We do not intend to follow the entire development of his theory, 

 but merely to trace his relations to science and the scientific spirit. 

 The rest of the first book and the whole of the second are taken up 

 with a descrijjtion of the action and properties of the primitive atoms, 

 of which he supposes all things to be composed. Amid some argu- 

 ments that appear reasonable, he brings forward a striking fallacy. 

 "If," says he, "matter is infinitely divisible, the greatest and the 

 least, consisting equally of an infinite number of parts, must be equal." 

 In other words, a mile and an inch are equal, for they each consist of 

 an infinite number of equally small parts. The mathematical imagi- 

 nation among the ancients must have been very little developed, if 

 such an argument passed muster with minds trained to the investiga- 

 tion of abstract truth. 



