4 EVOLUTION 



were not always as they are, but had somehow grown 

 out of simpler elements, struggled nearer and nearer to 

 the truth. In all the fragments of speculation that have 

 come down to us it is, of course, twisted into forms that 

 depart widely from the truth and mixed up with specula- 

 tions that seem to us grotesque. Nothing else could be 

 expected in that first faint dawn of knowledge. The 

 remarkable thing is that so many correct guesses for 

 they were little more than guesses, in the absence of 

 systematic observation and experiment are found 

 amongst the false ones. I will notice only the more 

 interesting points that were added to the original idea 

 as the school continued to dwell in it. 



Empedocles (born about 490 B.C.) thought out some- 

 thing like the doctrine of the struggle for life and 

 survival of the fittest, which seems so peculiarly modern. 

 Innumerable forms were begotten in the crystallisation 

 of the primitive elements, he said; of these many 

 perished because they were unfitted to live. A little 

 later Leucippus put forward the theory that the universe 

 is built up of tiny particles, which he called "atoms," 

 because he regarded them as the ultimate and indivisible 

 (a-tomos) elements. An infinite number of atoms, of 

 different sorts and sizes, tossing about during infinite 

 time in an infinite space, might produce the things that 

 actually exist amongst the myriads of chance forms they 

 would assume. This eternal tossing at hazard is quite 

 opposed to our knowledge of law in the universe, and we 

 now know that "atoms" are not indivisible; but the 

 atomic theory has played a great part in science and 

 continues to play it, with a modification in regard to the 

 constitution of the atom. Democritus (born about 460 

 B.C.) gave a firmer and more reasonable shape to the 

 idea of the atomic evolution of the universe, and a 

 century later Epicurus gathered together the speculations 



