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S IEN E Influence of  ekulé  Dream On Benzene Structure Disputed Scientists diff er on role of imaginati on and unconscious processes—such as Kekulé s vision of a snake biting its tail—in scientific advances Richard J. Seltzer,  C EN Washington Generations of chemistry students have cut their teeth on the tale of August Kekulé's dream—one of the most often retold anecdotes in the history of science. Dozing before the fireplace in the winter of 1861- 62 ,  the German chemist is pictured as having a vision of a snake biting its own tail. This dream inspired him to propose a ring structure for benzene in papers published in 1865 and 1866. His vision is called prob ably the most important dream in history since Joseph's seven fat and seven lean cows in Arthur Koest- ler's book on the creative process, The Act of Creation (Macmillan, New York, 1964). Knowledge of the benzene structure led directly to modern chemical industry based on structural organic chemistry, in par ticular the rise of the German coal tar dye and pharmaceutical indus tries in the final third of the 19th century. But did Kekulé really have the dream? There is no basis in truth for this attractive piece of chemi cal folklore, charge John H. Wotiz, professor of chemistry and biochem istry at Southern Illinois Universi ty, and Susanna Rudofsky, a research scientist in the department of mo lecular genetics and cell biology at the University of Chicago. indeed, Wotiz disputes the con cept in general of scientists' get ting their ideas in 'dreams/ That concept presents a damaging pic ture of scientists, and chemists in particular, to the public. Chem ists don't operate by dreaming up things. We do experimental work and get hard facts first. Then we formulate a chemical structure. We have to get out from under, the Kekulé myth. Since the summer of 1984, Wotiz and Rudofsky have disputed Kekulé's dream at scientific meetings, in cor respondence, and in the pages of t h e  Chronicle of Higher Education  and Chemistry in Bntain Their theses have been criticized in particular by Alan J. Rocke, associate professor in the Program for History of Science & Technology at Case Western Reserve University, and O. Bertrand Ramsay, chairman of the chemistry depart ment at Eastern Michigan Universi ty. And Rocke has just published a 27-page review in the journal  An - nals of  cience  [42, 355 (1985)], which he calls the most extensive discus sion of the origins of the benzene theory ever to appear. Wotiz: no basis in truth Wotiz and Rudofsky also outlined some of their theses at American Chemical Society national meetings in September and last spring. In deed, the Division of The History of Chemistry scheduled a debate be tween Wotiz and Rocke for the Sep tember meeting. However, Rocke withdrew from the debate, leaving Wotiz to present both sides of the dispute  himself Rocke says he with drew because it would not be useful to engage in polemics. It would turn into a circus. I've already said all I have to in published papers. The Illinois chemists' skepticism about Kekulé's dream stems from their examination of circumstances and historical records. The source of the dream story, they point out, is the published text of Kekulé's extemporaneous speech in 1890 at the Benzolfest, the 25th anniversa ry celebration in Berlin of his first paper on the cyclic structure of ben zene. Nothing had been published about the dream in the 28 or 29 years since he had supposedly ex perienced it. He also revealed at this ceremony that he had had an other dream, probably in 1855, lead ing to publication in 1858 of his paper formulating the basis of or ganic chemical structure theory—the tetravalency and linking of carbon atoms to each other. The Illinois chemists question whether Kekulé even mentioned the snake dream in his oral remarks, although he apparently mentioned his 1855 dream. They say that press accounts of the speech do not men tion the snake dream. And his re marks later, after writing down the speech for publication, indicate that if dreams were mentioned, it would have been in a humorous way and, therefore, not to be taken seriously. Moreover, Wotiz and Rudofsky find no hints of a dreamlike revela- 22 November 4, 1985 C EN

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S IEN E

Influence of  ekulé Dream

On Benzene Structure DisputedScientists differ on role of

imagination and unconscious

processes—such as Kekulé s

vision of a snake biting its

tail—in scientific advances

Richard J . Seltzer,  C EN Washington

Generat ions of chemis t ry s tudentshave cut their teeth on the tale ofAu g u s t Kek u l é ' s d ream —o n e o f t h emost of ten re to ld anecdotes in thehis tory of sc ience. Dozing beforethe f i rep lace in the winter of 1861-62 ,  the German chemis t i s p ic turedas having a v i s ion of a snake b i t ingi t s own ta i l . This dream inspi redhim to propose a r ing s t ructure forbenz ene in papers publ i shed in 1865an d 1866. His vision is cal led pro b

ably the mos t importan t dream inhis tory s ince Joseph ' s seven fa t ands ev en lean co w s i n Ar t h u r Ko es t-ler ' s book on the creat ive process ,

Th e Act of Cre at ion (Mac mi l lan ,Ne w York , 1964). Kno wled ge of th eb en zen e s t ru c t u re l ed d i r ec t l y t omodern chemical indus t ry based ons t ructural organic chemis t ry , in part icular the rise of the German coalt a r d y e an d p h a rm aceu t i ca l i n d u s tries in the final third of the 19thcen t u ry .

But d id Kekulé real ly have thedream ? The re i s no basi s in t ru thfor thi s at t rac t ive piece of che mi cal fo lk lore , charg e John H. Wo t iz ,professor of chemistry and biochemis t ry a t Southern I l l ino is Univers i ty, an d Su san na R udofsky, a researchscien t i s t in the depar tment of molecular genet ics and cel l b io logy a tthe Univers i ty of Chicago.

i n d eed , Wo t i z d i s p u t es t h e co n cept in gen eral of sc ien t i s t s ' get t ing thei r ideas in ' d r ea m s/ Thatco n cep t p res e n t s a d am ag i n g p ic

ture of sc ien t i s t s , and chemis t s inp a r t i cu l a r , t o t h e p u b l i c . C h em is t s don ' t operate by dreaming upt h i n g s . We d o ex p er i m en t a l wo rkand get hard facts fi rs t . Then weformulate a chemical s t ructure . Weh av e t o g e t o u t f rom u n d e r , t h eKek u l é m y t h .

S ince the summer of 1984 , Wot iz

and Rudofsky have disputed Kekulé'sdream at sc ien t i f i c meet ings , in correspondence, and in the pages ofth e Chronicle of Higher Education  an dChemistry in Bntain Their theses havebeen cri t icized in part icular by AlanJ. Rocke, associate professor in theProgram for His tory of Science &Technology at Case Western ReserveUniversi ty, and O. Bertrand Ramsay,chai rman of the chemis t ry depar t ment a t Eas tern Michigan Univers i ty . And Rocke has jus t publ i shed a27-page rev iew in the journal   An -nals of  cience  [42, 355 (1985)], whichhe cal ls the mos t ex tens ive d i scuss ion of the or ig ins of the benzenet h eo ry ev e r t o ap p ea r .

Wotiz: no basis in truth

Wotiz and Rudofsky a l so out l inedsome of thei r theses a t AmericanChemical Socie ty nat ional meet ingsin September and las t spr ing . Indeed , the Div is ion of The His toryof Chemis t ry scheduled a debate between Wot iz and Rocke for the Sept em b er m ee t i n g . Ho wev er , R o ck ewi t h d rew f ro m t h e d eb a t e , l eav i n g

Wot iz to present both s ides of thed i s p u t e himself Rocke says he withdrew because i t wo uld not be usefulto engag e in polemics . I t wo uld turninto a circus. I 've already said al l Ih av e t o i n p u b l i s h ed p ap e r s .

The I l l ino is chemis t s ' skept ic i smabout Kekulé ' s dream s tems f romthei r examinat ion of c i rcumstancesand h i s tor ical records . The sourceof the dream s tory , they poin t ou t ,i s the publ i shed tex t of Kekulé ' sex temporaneous speech in 1890 a tthe Benzol fes t , the 25th anniversary celebrat ion in Berl in of his fi rs tpaper on the cycl ic s tructure of benzen e . No t h i n g h ad b een p u b l i s h edabou t the dream in the 28 or 29years s ince he had supposedly exper ienced i t . He a l so revealed a tt h i s ce rem o n y t h a t h e h ad h ad an other dream, probably in 1855, leading to publicat ion in 1858 of hispaper formulat ing the bas i s of organic chemical s t ructure theory— thete t ravalency and l ink ing of carbonatoms to each o ther .

T h e I l l i n o i s c h e m i s t s q u e s t i o nwhether Kekulé even ment ioned thesnake dream in h i s ora l remarks ,a l t h o u g h h e ap p a re n t l y m e n t i o n e dhis 1855 drea m. They say that pres saccounts of the speech do not ment ion the snake dream. And h i s remarks la ter , af ter wri t ing down thespeech for publicat ion, indicate thati f d reams were ment ioned , i t would

h av e b een i n a h u m o ro u s way an d ,therefore, not to be taken seriously.

Moreover , Wot iz and Rudofskyf ind no h in t s of a drea ml ik e rev ela-

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t ion in Kekulé ' s papers on carbons t ructur e in 1858 or be nz en e s t ructur e in 1865 an d 1866. Inste ad, t he ysay , s ta tements in the 1865-66 papers ind icate Kekulé had formedhis ideas on benzene s t ructure seven years ear l i er .

In addi t ion , Wot iz bel ieves thatr i s i n g Germ an n a t i o n a l i s m —s t i m u l a t e d e s p e c i a l l y b y t h e F r a n c o -Pruss ian War (1870-71)—may haveinf luen ced Kek ulé in 1890 to a t t r ibu te concept ion of the benzene s t ruct u re t o a d ream , p res e rv i n g t h ei m ag e t h a t t h e t h en -n ew a ro m at i cchemistry was a s trict ly German scien t i f ic con t r ibu t ion . In th i s way ,he d id not hav e to cred i t fore igninvest igators —in part icular, Frenchchemis t Augus te Laurent , Scot t i shchem is t Arch ibald S . Cou per , a nd

Austrian chem ist Joseph Loschmidt—o n wh o s e s h o u l d e r s h e was s t an d i n g , an d wh o p reced ed Kek u l é i nwr i t ing cycl ic s t ructu res . As ev i dence of Kekulé ' s an t i fore ign b iasWot iz c i t es a l e t t er dur ing the warin which Kekulé refers to the Frenchas h u n d ev o l k ( s o n s o f b i t ch es ).

Rocke has spe nt 11 years as a h i s torian of chemistry intensively study ing Kekulé . Wot iz and Rudofsky ' sconclusions fly in the face of s tandard in terpreta t ions , he emphas izes ,an d they offer no persua s ive rea

s o n t o ch a n g e . He k n o w s o f n oprofess ional h i s tor ians of chemist r y w h o a g r e e w i t h W o t i z a n dRudofsky , and he and Ramsay f indthat few of the c la ims ma de int h e i r wo rk a re s u s t a i n ab l e .

There i s no reason to d i sbel ievewhat Kekulé h imsel f says about h i sd rea m , R o ck e ex p l a i n s . Th e ev i dence indicates that Kekulé d id reveal h i s two dreams in publ ic fort h e f i r s t t i m e i n h i s B en zo l fe s tspeech , and that those dreams d ido c c u r . K e k u l é a c c o m p a n i e d t h ewri t t en vers ion of h i s speech , in c lud ing the dream s tor ies , wi th ale t t er em pha s iz in g that th i s i s exac t l y h o w t h e s p eech was g i v en .Moreover , there are expl ic i t o r impl ic i t references to the dreams ins e v e n n e w s p a p e r r e p o r t s o n t h es p eech ( a l t h o u g h t h e re ' s n o  specif-i c me nt io n of snakes) .

F u r t h e rm o re , R o ck e an d R am s aypoin t ou t , i t i s na ive to seek ev i dence of the two dreams in K ekulé ' s1858 and 1865-66 pape rs . M id-19th

Rocke: no reason to disbelieve

century European science was strongly pos it iv i s ti c and ind uct iv i s t i c , a ndKeku lé wo uld op en h imsel f to imme diate ridicule if he referred in hispapers to insp i ra t ion f rom dreams.On the o the r han d , t e l l ing suchs t o r i e s a s a d i s t i n g u i s h e d e l d e rspokesman of sc ience a t an e labora te fes t ival in one ' s honor wouldbe a very d i f feren t ma t ter .

In addi t ion , there i s ev idence thatthe dream s tor ies were long fami l

iar to Kekulé ' s fami ly and f r iends .For example , h i s son S tephan wrotein 1927 that his father had told thed ream an e cd o t es r ep ea t ed l y t o f am i l y m em b ers , co l l eag u es , an d ac qua in tanc es . An 1886 paro dy of h i swh i r l i n g s n ak es i n t h e   ChemischeBerichte also indica tes fam il iari ty ofhis col leagues with the dream. Rockean d R am s ay r e j ec t t h e ch a rg e—wh ich Rocke says i s based on as i n g l e an t i -F ren ch co m m en t m ad ein a pr ivate l e t t er to a f r i end du r in gwar t i m e —t h a t Kek u l é was a x en o p h o b i c Germ an ch au v i n i s t . On t h eco n t ra ry , t h ey s ay , t h e ev i d en ceshows he was an in ternat ional i s t .

S u m m i n g u p t h e d i s p u t e , Wo t i zsays he has acted as a scient is t , basing his claims only on facts . Hebel ieves Rocke and Ramsay haven o t r e s p o n d e d a d e q u a t e l y t o h i sfindings. He urges that the two sidestry to resolve their differences in debate before an appropriate audience.

Rocke bel ieves the d i spute overKek u l é ' s d ream rea l l y co m es d o wn

to conf l ic t ing models of how scient i f i c advances come about . On ones ide , Wot iz bel ieves in a s t r i c t lyrat ional is t ic, posi t ivist ic process. Onthe o the r s ide , Rocke c ites the grow ing body of opin ion that creat ives c i e n t i f i c t h i n k i n g c a n n o t b e e x p la ined only in t erms of l inear , d i

rect log ic : Crea t ive mo me nts of tenc o m e t h r o u g h n o n r a t i o n a l p r o cesses . As d i scussed in Koes t ler ' sbook, many scien t i s t s have repor t ed d ay d ream s an d o t h e r m o m en t so f c r e a t i v i t y t h r o u g h t h e u n c o n s c i o u s —wh en t h ey were n o t t h i n k ing about sc ience.

His v iews are re inforced by not ed metal lurg i s t and h i s tor ian of sc i ence Cyri l S . Sm i th , p rofessor eme ri tus a t Massachuset t s Ins t i tu te ofTech nology . Sm i th bel ieves that a

fundamental ly new scien t i f i c ideaalways starts with a feel ing of cert a i n t y w i t h o n e ' s wh o l e b o d y , n o tj u s t w i t h t h e m i n d — a n e s t h e t i csense, a sensual s tep. This fi rs t s tepis absolutely essent ial : I t ' s l ike thenucleat ion s tep of a phase t rans i t ion . You get the nucleus of a newpat tern of thought , no t conceivedbefore , and i t can grow and prod u ce a n ew s t ru c t u re .

Indeed , Smi th te l l s C&EN, he bel i eves that pract ical ly every ne wscient i f i c theory comes about f rom

wh a t m i g h t b e ca l l ed d ay d ream s ,when a scient is t is not in a logicalbut in a sensua l mo de . This i s because som eth ing real ly new d oesn ' tfi t , i t must break away from establ i shed pat terns and seek a d i f feren tr e l a t i o n s h i p b e t ween co m p o n en t s .I t i s a lway s som eth i ng that i s i l log i cal w he n you first get it . H e stressesthat this is but the fi rs t s tep in theprocess . You the n mu s t app ly logic , mathem atics , and rigorous thou ghtto t es t and ex tend the ideas . Manynucle i are erased by th i s process :No t h i n g ev e r g ro ws o u t o f t h em .

Indeed , Rocke and Ramsay note ,t h e b en zen e t h eo ry d i d n o t en t e rKekulé ' s mind fu l ly formed v ia ad ream . He o n l y p u b l i s h ed i t s ev e r a l y ea r s l a t e r . He r e i t e r a t ed t h i st h e m e i n h i s B en zo l fe s t s p e ech .After descr ib ing the snake dream,he sa id , Let us l earn to drea m, an dperhaps then we wi l l f ind the t ru th .But l e t us a l so beware not to publ i sh our dream s unt i l they hav e be enex am i n ed b y t h e wak en ed m i n d . D

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