380 VITALITY 



The issue, however, must be tried, not on its consequences, but on its scimi- 

 tific merits ; on which grounds, as I apprehend, whatever may be demonstrated 

 concerning the vitality of man holds equally good with reference to the life of a 

 monad, or of a particle of red snow. Still, if it can be shown on purely physical 

 principles that vitality is a something which is not analogous to the actions of 

 known forces, then life is, to all intents and purposes, a miracle, by which I 

 understand not the action of a power in opposition to or thwarting the physical 

 laws of nature, but the manifestation of an agency extra-cosmical, working har- 

 moniously with, and by means of, those laws. 



It may seem to some hardly worth the while to contend for the possession by 

 man of a distinct vitality, if by this term is meant only that which he must hold 

 in common with an animalcule or a seed. But a moment's reflection will make 

 it plain how vast a step is taken if we gain from physical science the admission 

 that her kingdom is not universal. None will be more ready than the man of 

 science to confess how little is that which is known when compared with that which 

 remains to be known ; nevertheless he is becoming more and more inclined to 

 be convinced that all is knoivahle, and, if known, would be found conformable 

 in all respects with the knowledge that he has already. Now, if it can be shown 

 that vitality, even in a vegetable cell, is a thing which lies beyond the cope of 

 phpsical investigation, the spell is broken, and a claim is established for the 

 determination of what may or may not constitute the higher faculties of man on 

 other grounds than those of physical science alone. 



As a believer in something more than natural science, it is proper for me to 

 state that I do not think a rational persuasion of the personality of man must 

 rest upon evidence to be obtained from physical researches. Still I should 

 expect to find in physical science some indication of its own limits, and of the 

 commencement of that border land which separates the known from the un- 

 known. More than this the very nature of the case forbids. 



We may now proceed to the consideration of the two propositions given at the 

 commencement of this paper as expressing the views of certain physiologists 

 who decline to recognize in vitality anything beyond the operation of forces 

 amenable to physical investigation. 



It will be observed at the outset that much stress is laid upon the absence of 

 all knowledge respecting the nature of vitality. This limitation is needful, be- 

 cause to say that nothing is known of its effects would simply be to anticipate 

 the decision of the question at issue. But it may at once be admitted that we 

 know nothing of the nature of vitality. How should we, if it has no analogy 

 with any of the known forces ? For, on this supposition, in what form could 

 knowledge of vitality hold its place in our minds ? Not in any of the old familiar 

 forms, such as predicates respecting its quantity, intensity, polarity, and the 

 like ; for the thing thus known would have analogy with known forces, and 

 would not be a thing sui generis, but would fall naturally into some recognized 

 category. We have to give our reasons for concluding that certain observed 

 facts imply the existence of an agency quite unlike any of the forces known to 

 us. The reply that we know nothing of the nature of such an agency is cer- 

 tainly no disparagement to our hypothesis, unless it may be shown that nothing 

 can exist of which we do not know the nature. If, then, we are at liberty to 

 make the supposition that vitality is a thing sui generis, that we know nothing 

 of its nature tells neither for nor against the probability of its existence. 



One of the broadest generalizations deducible from the immense additions 

 recently made to the ascertained truths of science is, that numberless things 

 previously supposed to be distinct are now found to be so closely related that it 

 is impossible to draw a line of separation between them. This has been the case 

 alike with things organic and inorganic. The great kingdoms of animal and 

 vegetable life pass quite imperceptibly the one into the other; and in both king- 

 doms the number of classes, orders, families, genera, and species that show the 



