532 



NA TURE 



\Oct. i8, 1877 



The pioblein 0/ a natural phenomenon is an algebraic equation 

 with many unknown factors. The practical man looks at the 

 equation and tries to solve it, substituting for one or the other 

 unknown factor a generally large and decisive value ; the proof 

 of correctness he docs not attempt. It is easy to see that 

 in this manner the solution — and with it the true underi'-snding 

 — will certainly not be attained in all eternity. 



The solution of an equation with many unknown factors 

 is only possible if just as many equations can be obtained as 

 there are unknown factors, and if tlie same unknown factors are 

 contained in all. As this is generally impossible [with natural 

 phenomena we try to get equations in which there is only one 

 unknown factor. This is done by scimtific experiment (not by 

 the so-called experiment of these practical men) in which all 

 unknown factors are removed save one, and by which the value 

 and effect of this one can be securely determined. 



For a long time physics has adopted this way of scien- 

 tific experiment. Physiology has only recently recognised it in 

 a more general manner as the only correct one. It is true that 

 by this tedious and time-devouring but yet exclusively safe 

 and progressive method we do not erect large edifices of sys- 

 tems which are only fated to fall to pieces again shortly, but 

 we gain simple facts, perhaps insignificant by themselves, but 

 v/hich retain their value for ever and enable us to find new 

 facts. Thus the stock of recognised facts increases slowly but 

 securely. A snail which takes the straight road for its goal 

 progresses, while a grasshopper, with its bounds in all directions, 

 remains always on the same spot. Thus scientific investigation 

 proves to the empirics by facts, that by the exact method certain 

 and permanent knowledge of natural phenomena may be gained. 



Many methodical investigators who by the exact method 

 augment the stock of permanent facts, when asked for the limits 

 of natural knowledge, an A thinking a solution based upon 

 principles inadmissible, simply reply, "Belief always begnis 

 where knowledge ceases." In saying so the course of their 

 thoughts runs thus : Humanity faces the totality of nature. Its 

 insight constantly masters new domains by dint of meditation 

 and investigation. Thus, for example, in the present time we 

 have progresssed much further in the knowledge of nature than 

 was the case during the middle ages and antiquity, and Euro- 

 pean civilisation is far ahead of that of the rest of humanity. 

 With progressing mental work the empire of knowledge always 

 increases in extent, and the domain where we must be satisfied 

 witli belief decreases as constantly. 



This conception has an undeniable value in a certain regard. 

 It gives us a measure of the height which scientific natural 

 knowledge had generally attained in every century, and at the 

 same time a special measure for the different human races and 

 nations, lor the different classes in a nation, and finally for every 

 single individual. Considerations of this nature have as much 

 scientific interest to the historian and anthropologist, as practical 

 interest to the theoloyist, the politician, and a number of others. 



The phrase that belief begins where knowledge ceases is an 

 actual sohition of the question for certain ends. Eut with this 

 our interest is not s-atisfied. We turn to the theoretical part 

 of ihe problem with special sympathy. We wish to know 

 whether the limit where human knowledge must stop can be 

 determined at all or not — if yes, hoiv far our understanding may 

 penetrate into nature, how much humanity may scientifically 

 understand of nature, if during an immeasurable period, let us 

 say at once during eternity, it is occupied with natural inves- 

 tigations, assisted by all imaginable means— what are the 

 boundaries, therefore, which the scientific understanding of 

 nature can never and under no conditions overstep ? what is 

 the fundamental limit between the empire of knowledge and 

 that of belief? 

 _ This question deseives all the more to be seriously investigated 

 since it is well known that from two opposed sides the absolute 

 pjwer of the human mind over na:ure is claimed with complete 

 certainty— with decreasing energy by the natural philosophers, 

 with increasing energy by materialists. The former think they 

 can construct lormal nature out of herself, and natural know- 

 ledge for them only consists in finding fthe concrete natural phe- 

 nomena for the constructed abstract ideas, where, of course, 

 they can in no point be freed from the self-deception that they 

 construct the ideas according to conceptions by the senses 

 instead of out of themselves. The latter admit only force and 

 matter in lime and space ; and that man, who is built up of 

 matter and force, shall master nature, which is built up of the 

 same factors, stems to them a reasonable idea. Loth, natural 

 philosophers as well as materialist ■■, raise man to 0, flattering 



h'-ighf, with regard tj his own consciousness and pride; they 

 declare him lord of the world, not the real lord who makes the 

 world, it is true, but yet the imaginary lord, who understands 

 the work of the real lord. Can we lay cliim with good reason 

 this eminent position ? 



Many have often tried to answer this question from different 

 points of view ; perhaps one of the best replies was given by 

 my predecessor in this assembly. Prof. Du Bois Reymond, in his 

 much-talked-of and often misunderstood address, "On the Limits 

 of Natural Knowledge." I shall only consider this latter reply, 

 which, in an intellectual manner and in rich, poetical language, 

 adoins and covers the gems of thought with the most beautiful 

 flowers of speech. It would have been useful, and would have 

 shov.'n the right way to many a one who cannot so easily get at 

 the kernel through the shell, if result and proof had been 

 comprised in a few short phrases. 



The speaker, like the conqueror of a world in the olden times 

 on a day of rest, wishes to point out clearly the true limits of 

 the immeasurable empire which world-conquering natural science 

 has subjected to its understanding, and arrives at the following; 

 three conclusions : — I. Natural knowledge, or understanding, is 

 the reduction of a natural phenomenon to the mechanics of 

 s'mple and indivisible atoms. 2. There are no atoms of this 

 description, and therefore there is no real understanding. 

 3. Even if we could understand the world through the mechanics 

 of atoms, we could nevertheless not understand sensation and 

 consciousness through it. 



General understanding would no doubt have been facilitated 

 considerably if these results had not been introduced as the 

 limits of natural knowledge, but as the impossibility and futility 

 of natural knowledge. Because, since the speaker does 

 not go beyond this negation, investigating natural science cannot 

 define the limits of a domain which she does not even possess — 

 and if she is even deprived for ever of all insight into material 

 phenomena, it can hardly matter to her, as a deposed potentate, 

 whether or not she might claim the spiritual domiin, in case of 

 a supposed accession to power. 



We may perfectly agree with Du Bois Reymond's thoughts, 

 and yet be convinced that they are not complete and all-com- 

 prising enough to define na'ural knowledge in all directions, that 

 in their incompleteness they lead to false deductions wdiich 

 contradict our natural scientific conscience, and that it is 

 desirable to treat this question not only on the negative side, but 

 to examine whether the human mind is not capable of natural 

 knowledge, of what nature this knowledge is, and what is its 

 e:<tent. 



The solution of the question ; In what way and how far may 

 I know and understand nature? is evidently determined by three 

 dilTertnt things, viz., by the answers to three questions; — ^(i) 

 The condition and capacity of the Ego ; (2) the condition and 

 accessibility of nature ; and (3) the demands which we make 

 of knowledge. Subject, object, and copula therefore partici- 

 pate in the solution. A separation of this kind may perhaps be 

 thought supeifluous, perhaps even inadmissible, because it may 

 be said that the understanding of the object by the subject is an 

 indivisible process. And yet it is correct, because consideration 

 gives prominence now to the one and now to the other factor, 

 and it is also useful, because it requires exhaustive treatment. 

 The difficulties which are in the way of knowledge with regard 

 to the suliject or object, are even most conspicuous if we entirely 

 remove one of the two factors by supposing that it offers no 

 difficulties at all. With regard to the capacity of the Ego to 

 understand the phenomena of nature, the undoubted fact is 

 decisive, that our power of thinking, in whatever condition it may 

 be, only gives us nature as we perceive her by our five senses. 

 If we could not see nor hear anything, nor smell, taste, nor 

 touch anything, we would not know at all that there is anything 

 besides ourselves, nor indeed that we are in bodily existence 

 ourselves. 



The condition with regard to ths correctness of our concep- 

 tions therefore always exists — that our external and internal 

 senses report correctly. Our knowledge is only correct in so 

 far as observation by the senses and internal perception (die 

 innerc Vcnnil/duiii;) ats correct. But an infinitely great proba- 

 bility exists that both, after all, lead us to objective truth, 

 because the errors committed by the single individual or by all, 

 are finally always recognised and proved as such, and because 

 natural science, the further it progresses, knows how to remove 

 more and more all apparent contradictions, and how to make 

 all observations agree amongst themselves. 



If we remain satisfied in this direction, the question arises, 



