I] OF VITAL PHENOMENA 19 



least of it, a close analogy with known physical phenomena : and 

 to this matter we shall presently return. But though they resemble 

 known physical phenomena, their nature is still the subject of much 

 dubiety and discussion, and neither the forms produced nor the 

 forces at work can yet be satisfactorily and simply explained. We 

 may readily admit then, that, besides phenomena which are obviously 

 physical in their nature, there are actions visible as well as invisible 

 taking place within living cells which our knowledge does not permit 

 us to ascribe with certainty to any known physical force; and it 

 may or may not be that these phenomena will yield in time to the 

 methods of physical investigation. Whether they do or no, it is 

 plain that we have no clear rule or guidance as to what is "vital" 

 and what is not; the whole assemblage of so-called vital phenomena, 

 or properties of the organism, cannot be clearly classified into those 

 that are physical in origin and those that are sui generis and peculiar 

 to living things. All we can do meanwhile is to analyse, bit by bit, 

 those parts of the whole to which the ordinary laws of the physical 

 forces more or less obviously and clearly and indubitably apply. 



But even the ordinary laws of the physical forces are by no means 

 simple and plain. In the winding up of a clock (so Kelvin once 

 said), and in the properties of matter which it involves, there is 

 enough and more than enough of mystery for our limited under- 

 standing: "a watchspring is much farther beyond our understanding 

 than a gaseous nebula." We learn and learn, but never know all, 

 about the smallest, humblest thing. So said St Bonaventure : " Si per 

 multos annos viveres, adhuc naturam unius festucae seu muscae seu 

 minimae creaturae de mundo ad plenum cognoscere non valeres*." 

 There is a certain fascination in such ignorance ; and we learn (like 

 the Abbe Galiani) without discouragement that Science is "plutot 

 destine a etudier qu'a connaitre, a chercher qu'a trouver la verite." 



Morphology is not only a study of material things and of the forms 

 of material things, but has its dynamical aspect, under which we 

 deal with the interpretation, in term^ of force, of the operations of 

 Energyf . And here it is well worth while to remark that, in deahng 



* Op. V, p. 541 ; cit. E. Gilson. 



t This is a great theme. Boltzmann, writing in 1886 on the second law of 

 thermodynamics, declared that available energy was the main object at stake 

 in the struggle for existence and the evolution of the world. Cf. Lotka, The 

 energetics of evolution, Proc. Nat. Acad. Sci. 1922, p. 147. 



