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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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