POPULAR SCIENTIFIC LECTURES. 



law, the business of deduction comnifncrr,. 

 It is then our duty to develop the conf>- 

 quences of our law as completely as may be, 

 but in the iirst place only to apply to them 

 the test of experience, so far as they can be 

 tested, and then to decide by this test 

 whether tho law holds, and to what extent. 

 This is a test which really never ceases: 

 The truo natural philosopher reflects at each 

 new phenomenon, whether the best estab- 

 lished Liws of the best known forces may not 

 experience a change ; it can of course only 

 be a question of a change which does not 

 contradict the wkolo store of our previously 

 collected experiences. It never thus attains 

 unconditional truth, but such a high degree of 

 probability that it is practically equal to cer- 

 tainty. The metaphysicians may amuse them- 

 selves at this ; we will take their mocking to 

 heart when they are in a position to do bet- 

 ter, or even as well. The old words of Soc- 

 rates, the prime master of inductive defi- 

 nitions, in reference to them are just as fresh 

 as they were two thousand years ago : " They 

 imagined they knew what they did not know, 

 and he at any rate had the advantage of rwyt 

 pretending to know what he did not know." 

 And again, ho was surprised at its not being 

 clear to them that it is not possible for men 

 to discover such things ; since even those 

 who most prided themselves on the speeches 

 made on the matter, did not agree among 

 themselves, but behaved to each other like 

 madmen (ro, ; ; [iaiv<>fj.ivoi$ OMO'U?). Socrate:> 

 calls them rotJS/^yzTT-oix^oi'oi'vra?. Schopen- 

 hauer calls himself fi Mont Blanc, by the 

 side of a mole-heap, when he compares him- 

 self with a natural philosopher. The pupils 

 admire these big words and try to imitate 

 the master. 



In speaking against the empty manufacture 

 of hypotheses, do not by any means suppose 

 that I wish to diminish the real value of orig- 

 inal thoughts. The first discovery of a new 

 law is the discovery of n similarity which 

 has hitherto been concealed in the conrso of 

 natural processes. It is a manifestation of 

 that which our forefather* in a serious sense 

 described as " wit ;" it is of the same quality 

 as the highest performances of artistic per- 

 ception in the discovery of new types ot ex- 

 pression. It is something which cannot bo 

 forced, and which cannot be acquired by any 

 known method. Hence all tlioso aspire after 

 it who wish to pass as tho favored children 

 of genius. It seems, too, so easy, s:> free 

 from trouble, to get by sudden mental flashes 

 an unattainable advantage over our contem- 

 poraries. Tho true artist and the true in- 

 quirer know.} that great works can only ba 

 produced by hard work. Tho proof that the 

 ideas formed do not merely scrape together 

 superficial resemblances, but are produced 

 by a quick glance into tho connection of tha 

 whole, can only bo acquired when these 

 ideas are completely developed that is, for 

 a newly discovered natural law, only by its 

 agreement with facts. This estimate must 

 by no means bo regarded as depending on 

 external success, but tho success ia here 



closely connected with the depth and com- 

 pleteness of the preliminary perceptions. 



To find superficial resemblances is easy ; it 

 is amusing in society, and witty thoughts 

 soon procure for their author tho name of a 

 clever man. Among the great number of 

 such ideas, there must bo some which are 

 ultimately found to be partially or wholly 

 correct ; it would be a stroke of skill always 

 to guess falsely. In such a happy chance a 

 man can loudly claim his priority for tho dis- 

 covery ; if otherwise, a lucky oblivion con- 

 ceals tha false conclusions. Tho adherents 

 of such a process are glad to certify the value 

 of a first thought. Conscientious workers 

 who are shy at bringing their thoughts before 

 the public before they have tested them in 

 all directions, solved all doubts, and have 

 firmly established the proof, these are at a 

 decided disadvantage. To settle the present 

 kind of questions of priority, only by tho 

 date of their first publication, and without 

 considering the ripeness of the research, has 

 seriously favored this mischief. 



In the " type case" of the printer all tha 

 wisdom of the world is contained which has 

 been or can be discovered ; it is only requi- 

 site to know how the letters are to be arranged. 

 So also, in the hundreds of books and pam- 

 phlets which are every year published about 

 ether, the structure of atoms, the theory of 

 perception, as well as on tne nature of the 

 asthenic fever and carcinoma, ail the most 

 refined shades of possible hypotheses are ex- 

 hausted, and among these there must neces- 

 sarily be many fragments of the correct 

 theory. But who knows how to find them '! 



I insist upon this in order to make clear 

 to you that all this literature, of untried and 

 unconfirmed hypotheses, has no value in 

 the progress of science. On the contrary, 

 tho few sound ideas which they maj- contain 

 are concealed by the rubbish of tho rest ; and 

 one who wants to publish something really 

 new facts sees himself open to the danger 

 of countless claims of priority, unless he is 

 prepared to waste time and power in reading 

 beforehand a quantity of absolutely useless 

 books, and to destroy his readers' patience 

 by a multitude of useless quotations. 



Our generation has had to suffer under the 

 tyranny of spiritualistic metaphysics ; tha 

 newer generation will probably have to guard 

 against that of the materialistic hypotheses. 

 Kant's rejection of the claims of pure thought 

 has gradually made some impression, bul 

 Kant allowed oneway of escape, it was as 

 clear to him as to Socrates that all metaphysi- 

 cal systems which up to that time hurl been 

 propounded were tissues of false conclusions. 

 Jlis " Kritik der reinen Vernuiift ' is n con- 

 tinual sermon against the use of tho category 

 of thought beyond the limits of possible ex- 

 perience. But geometry seemed to him to 

 do something which metaphysics was stn vine; 

 after ; and hence geometrical axioms, which 

 he looked upon as d priori principles antooe- 

 deut to all experience, ho held to be ^ivpn by 

 transcendental intuition, or as the inherent 

 form ul. all external intuition. Since thai 



