THE ORIGIN OF LIFE 173 



nor a force. In other words, it is totally removed from the 

 category of efficient or active causes. The second difference 

 between Driesch and Aristotle with respect to the use of 

 the term entelechy lies in the fact that Driesch uses it as a 

 synonym for the soul or vital principle, whereas, according 

 to Aristotle, entelechy is common to the non-living units of in- 

 organic nature as well as the living units (organisms) of the 

 organic world. All vital principles or souls are entelechies, but 

 not all entelechies are vital principles. All material beings 

 or substances, whether living or lifeless, are reducible, 

 in the last analysis, to two consubstantial principles or 

 complementary constituents, namely, entelechy and mat- 

 ter. Entelechy is the binding, type-determining principle, 

 the source of unification and specification, which makes 

 of a given natural unit (such as a molecule or a proto- 

 zoan) a single and determinate whole. Matter is the de- 

 terminable and potentially-multiplei element, the principle 

 of divisibility and quantification, which can enter indifferently 

 into the composition of this or that natural unit, and which 

 owes its actual unity and specificity to the entelechy which 

 here and now informs it. It is entelechy which makes a 

 chemical element distinct from its isobare, a chemical com- 

 pound distinct from its isomer, a paramoecium distinct from an 

 amoeba, a maple distinct from an oak, and a bear distinct 

 from a tiger. 



The molecular entelechy finds expression in what the or- 

 ganic chemist and the stereochemist understand by valence, 

 that is, the static aspect of valence considered as the struc- 

 tural principle of a molecule. Hence it is entelechy which 

 makes a molecule of urea [0:C:(NH2)2] an entirely dif- 

 ferent substance from its isomer ammonium cyanate 

 [NHi'O'CiN], although the material substrate of each of these 

 molecular units consists of precisely the same number and 

 kinds of atoms. Similarly, it is the atomic entelechy which 

 gives to the isotopes of Strontium chemical properties differ- 

 ent from those of the isotopes of Rubidium, although the mass 



