Mechanistic Biology 227 



And this same argument establisheth 

 That nature of mind and soul corporeal is, 

 For when 'tis seen to drive the members on, 

 To snatch from sleep the body and to change 

 The countenance, and the whole state of man. 

 To rule and turn — what yet could never be 

 Failing a contact — Must we not grant they are 

 Of a corporeal nature ? 



Now of what body, what components, formed ' 

 Is this same mind I will go on to tell. 

 First I aver, 'tis superfine, composed. 

 Of tiniest particles — that such the fact 

 Thou canst perceive if thou attend from this : 

 Nothing is seen to happen with such speed 

 As what the mind proposes and begins. 

 Therefore the same bestirs itself more swiftly 

 Than aught whose nature's palpable to eyes. 



Lucretius differs from Democritus on many points, but, like 

 him, supposes that the soul, though it has directive power over the 

 body, is yet itself material subject to the laws governing the atoms 

 and must perish accordingly with the body. This is different to the 

 post-renaissance theories, which often admit that the mind is non- 

 material but deny it any action on the body, treating it as a shadow 

 thrown off by the body's physical processes, an " Epiphenomenon." 

 Where Lucretius exactly anticipates the epiphenomenalists of 

 modern times is in his refusal to believe that there can be such a 

 thing as psycho-physical action. This may show us how insepar- 

 able the problem of mechanism in biology is from that of psycho- 

 physical interaction. The latter is the real problem, but the former 

 has its roots in experimental work, and has to be solved first. As 

 against the mechanism of Lucretius it is instructive to note what 

 Tertullian says. Strangely enough, Tertullian upheld the cor- 

 poreal nature of the soul as against Plato, but that did not prevent 

 him from decrying mechanism in biology. In his treatise " De 

 Anima " he says : 



" In the first place there is in the soul some supreme principle 

 of vitality and intelligence which can be called the ruling power 

 of the soul — TO r\-^t\\i.o'^\.yja^. For if this be not admitted the 

 whole condition of the soul is put in jeopardy. Indeed, those men 



