Dec. 12, i8;8] 



NATURE 



135 



Having now endeavoured to recall to you some of the great 

 advances in science made during the last few years, it remains for 

 me, after the distribution of the medals awarded by your Council, 

 to retire from the Presidency in which I have so long experienced 

 the generous support of your officers and yourselves. This support, 

 for which I tender you my hearty thanks, together with my sense 

 of the trust and dignity of the office, and the interest attached to 

 its duties, has rendered my resignation of it a more difficult step 

 than I had anticipated. My reasons are, however, strong. They 

 tre the pressure of official duties at Kew, which annually increase 

 in amount and responsibility, together with the engagements I 

 am under to complete scientific works, undertaken jointly with 

 other botanists, before you raised me to the Presidency, and 

 the indefinite postponement of which works delays the publi- 

 cation of the labours tf my coadjutors. I am also influenced by 

 the consideration that, though wholly opposed to the view that 

 the term of the Presidency of the Royal Society should be either 

 short or definitely limited, this term should not be very long ; and 

 that, considering the special nature of my own scientific studies, 

 it should, in my case, on this as well as on other grounds, be 

 briefer than might otherwise be desirable. Cogent as these 

 reasons are they might not have been paramount were it not that 

 we have among us one pre-eminently fitted to be your Pre- 

 sident by scientific attainments, by personal qualifications, and 

 by intimate knowledge of the Society's affairs ; and by calling 

 upon whom to fill the proud position which I have occupied, you 

 are also recognising the great ser\ices he has rendered to the 

 Society as its treasurer for eight years, and its ofttimes munificent 

 benefactor. 



HAECKEL ON THE LIBERTY OF SCIENCE 

 AND OF TEACHING 



II. 



C^ H APTER V. treats of the methods of teaching, and contrasts 

 ^^ the genetic method, as advocated by Haeckel, with the 

 dogmatic one recommended by Virchow, The sensation which 

 Virchow's address caused in wider circles was only partly the 

 result of his opposition to the descent theory ; its principal cause 

 was his surprising conclusions with regard to the liberty of teach- 

 ing. Virchow demands that in the school — from the elementary 

 school up to the university — nothing should be taught -which is not 

 absolutely certain ; only objeetife but no subjective kno wledge is to be 

 communicated to the pupils by the teacher ; only facts, no hypo- 

 theses. Haeckel remarks that rarely has an eminent representa- 

 tive of science made such an attack upon the liberty of science 

 as did Virchow at Munich. "Where," he asks, "are we to 

 find the limits between subjective and objective knowledge?" 

 According to his conviction no such limit exists, and all human 

 knowledge as such is subjective. ' ' An objective science consisting 

 only of facts, without subjective theories, cannot be imagined." 

 He then proceeds to review various sciences in turn, and to 

 point out how much objective knowledge and "facts," and how 

 much subjective knowledge and "hypotheses" they contain. 

 He begins with Mathematics as the science which is eminently 

 <iie most certain one of all: "What about the simplest and 

 deepest maxims upon the firm basis of which the whole 

 proud building of mathematics rests? Can they be proved 

 for certain ? CerUinly not ' The most fundamental maxims 

 are indeed 'maxims,' and incapable of 'proof.' Only in 

 KxAtx to show by an example how even the first mathematical 

 maxims may be attacked by sceptics and shaken by philosophical 

 speculation we recall the recent discussions regarding the three 

 dimensions of space and the possibility of a fourth dimension, 

 discussions which are still continued by a number of the most 

 illustrious mathematicians, physicists, and philosophers. So 

 much is certain that mathematics is absolutely objective as little as 

 Any other science, but has a subjective basis in man's own nature. 

 . . . But even if we own that mathematics is an absolutely cer- 

 tein and objective science, how about all other sciences ? No 

 doubt those are ' most certain ' amongst the ' exact ' sciences, 

 toe maxims of which are founded on pure mathematics, in the 

 brst Ime therefore a great part oi physics. We say a great part, 

 because another great part— upon close examination by far the 

 greater— IS mcapable of an exact mathematical foundation. Or 

 wliat we do know with certainty about the essence of matter or 



ViL'hnw* iS^-^^v ^^'^tJ ""'^ ''■"^^^ Lehre. Eine Entgegnung au£ Rudolf 

 ^now s Munchener Rede uber " die Frcihelt der Wissenschaft im modernen 

 *wat. Von Ernst Haeckel. Cont nued from p 115. 



the essence of force? What do we know for certain about 

 gravitation, about mass-attraction, about action at a distance, 

 &c. ? We look upon Newton's gravitation theory, the basis of 

 mechanics, as the most important and most certain theory of 

 physics, and yet gravitation itself is only a hypothesis. And 

 then the other branches of physics — electricity an i magnetism, 

 for instance. The whole knowledge of these important branches 

 is based upon the hypothesis of ' electric fluids ' or of imponder- 

 able substances, the existence of which is certainly not proved. 

 Or optics ? No doubt optics belongs to the most important and 

 most complete branches of physics, yet the vibration theory, 

 which to-day we consider to be its indispensable basis, rests 

 upon a hypothesis which cannot be proved, viz., upon the 

 ' subjective ' supposition" of the li^ht-ether, the existence of 

 which nobody can objectively prove. Nay, even more ; before 

 Young established the vibration theory of light, the emanation 

 theory taught by Newton reigned supreme in physics for 

 centuries ; this theory has to-day been abandoned as im- 

 tenable. According to our view the mighty Newton ac- 

 quired the greatest merit with regard to the development 

 of optics, as he made the first attempt to connect and 

 explain the mass of objective optical facts by a subjective 

 leading hypothesis. But according to Virchow's view Newton 

 sinned most heavily by teaching this false hypothesis ; because 

 in ' exact ' physics only single and certain Jacts are to be taught 

 and to be ascertained by ' experiment as the highest means 

 of proof ; ' but physics as a -whole, resting as it does upon a num- 

 ber of unproved hypotheses, may be the object of research, 

 but must not be taught ! " Turning to Chemistry, Haeckel 

 shows that its objectiveness stands upon still weaker feet than 

 that of physics. Here the whole of the science is built upon 

 the hypothesis of the existence of atoms, a hypothesis as un- 

 proved and as incapable of proof as any. No chemist has ever 

 seen an atom, and yet he thinks the mechanics of atoms the 

 highest problem of his science, and describes and constructs the 

 positions and groupings of atoms, as if they were before him on 

 his dissecting table. According to Virchow, we therefore ought 

 to banish chemistry from the school and teach only the properties 

 of bodies and their reactions, which can be shown to the pupils 

 as " certain facts." This matter becomes still more ludicrous 

 when we tirni to the other sciences, which are all more or less 

 historical, and therefore do not possess that " half -exact " basis 

 upon which chemistry and physics rest. Geology, for instance, 

 would, according to Virchow, have to confine itself to the 

 description of certain facts, i.e., the structure of rocks, the forms 

 of fossils, the shape of crj-stals, &c., but would in the school 

 have completely to abandon all speculation regarding the deve- 

 lopment of the earth's crust, i.e., nothing but unproved hj^po- 

 theses from b^inning to end. We" might not even teach that 

 fossils are the actual remains of organisms which existed in former 

 periods, because even this is an " unproved " hypothesis. Even 

 down to the eighteenth centiu-y many eminent naturalists believed 

 fossils to be "freaks of nature," an enigmatic " lusus natural' 

 In a later part of his address Virchow admits fossils as "objec- 

 tive material proofs ; " but even here we may go no further than 

 our actual experience allows, and we may not draw subjective 

 deductions from the objective facts. Virchow's remark about 

 quaternary man being an "accepted fact" aflFords Haeckel 

 an opportunity for pointing out his inconsistency, and the un- 

 certainty and vagueness of most hypotheses concerning the age 

 and the first geological occurrence of man ; indeed, the distinc- 

 tion of a tertiary and a quartery age in itself is nothing but a 

 geological hypothesis. " Virchow tells us that never has a fossil 

 ape skull been found which really belonged to a human pro- 

 prietor, and that we cannot consider it as a revelation of science, 

 we cannot teach, that man descends from the ape or from any 

 other animal. If that be true, then nothing remains but the 

 descent from a god or from a clod of earth." 



Zoology, botany, and other biological doctrines do not fare 

 better, if we consider them in the light in which Virchow would 

 have them taught. Haeckel shows the utter untenability of 

 Virchow's demands, since no science, not even history, and cer- 

 tainly not philosophy, could be tolerated in our schools ; indeed, 

 the only one which could remain would be theology. " Incredible 

 as it seems, Virchow, the sceptical antagonist of dogmas, the 

 combatant for the liberty of science, now finds the only certain 

 basis of instruction in the dogma of Church religion. After all 

 that has happened the following phrase leaves no doubt on this 

 point : — 'All attempts to transform our problems into doctrines, 

 to introduce our theories as the basis of a plan of education, par- 



