June 13, 1902.] 



SCIENCE. 



925 



but where we also are; have seen some 

 handbreadths deeper than we see into the 

 deep that is infinite, without bottom as 

 without shore." 



"Philosophy complains that custom has 

 hoodwinked us from the first; that we do 

 everything- by custom, even believe by it; 

 that our very axioms, boast as we may, 

 are oftenest simply such beliefs as we have 

 never heard questioned. Innumerable are 

 the illusions of custom, but of all these 

 perhaps the cleverest is her knack of per- 

 suading us that the miraculous, by simple 

 repetition, ceases to be miraculous!" 



A lesson for vis, as people who are most 

 of us interested in science, showing how lit- 

 tle its most fixed conclusions may be worth, 

 may perhaps be conveyed in an example. 

 A century and a half a^o, when the new 

 science of chemistry won its first triumphs, 

 the fundamental discovery which was to 

 illuminate the whole science, the settled 

 acquisition which it seemed to have brought 

 to us, the thing which was going to last, 

 was 'phlogiston.' 



This had everything to recommend it, 

 in universal acceptance, and in what 

 seemed to the foremost men of the time, its 

 absolute certainty. 



"If any opinion," says Priestley, "in all 

 the modern doctrine concerning air be well 

 founded, it is certainly this, that nitrous 

 air is highly charged with phlogiston. If 

 I have completely ascertained anything at 

 all relating to air, it is this." 



I am trying here to say that laws 

 of nature are little else than man 's hypoth- 

 eses about nature. 



Phlogiston was then to the science of a 

 former age, in this sense a law of nature, 

 at least as great a generalization as the 

 kinetic theory of gases is to us; as widely 

 accepted, as firmly believed and as certainly 

 known— but what has become of it now? 



Can we tell, then, in advance by any 

 criterion what a 'law of nature' is? 



With a curious begging of the question 

 some answer, 'Yes, for laws of nature have 

 this distinction, that they have never been 

 disproved.' As if one were to say. Yes, 

 because when they are disproved we deny 

 that they are laws of nature ! 



Those of us who are capable of being in- 

 structed or warned by the history of hu- 

 man thought may, then, ask what kind 

 of a guarantee are we to have for any other 

 'fact' of our new knowledge? May they 

 not— all these 'facts'— be gone like the 

 baseless fabric of this vision, before an- 

 other hundred years are passed? 



The physical sciences seem to have had 

 less change in their theories than the 

 mighty displacements in other branches of 

 natural knowledge, but it is a truism to say 

 that all are changed, and it should be a tru- 

 ism to add that the 'laws of nature' are not 

 to us what they were a hundred years ago. 



I repeat that of the 'order' of nature we 

 may possibly know a little; but what are 

 these 'laws' of nature? What celestial 

 act of congress fixed them? In what stat- 

 ute book do we read them ? What guaran- 

 tees them? Our mistake is in believing 

 that there is any such thing, apart from 

 our own fallible judgment, for the thing 

 which the 'laws of nature' most absolutely 

 forbid one generation to believe, if it only 

 actually happens, is accepted as a part of 

 them by the succeeding. 



Suppose that a century ago, in the year 

 1802, certain French Academicians, be- 

 lieving like every one else then in the ' laws 

 of nature, ' were invited, in the light of the 

 best scientific knowledge of the day, to 

 name the most grotesque and outrageous 

 violation of them which the human mind 

 could conceive. I may suppose them to 

 reply, 'if a cartload of black stones were 

 to tumble out of the blue sky above us, be- 

 fore our eyes, in this very France, we 



