ABSTRACT
EMPEDOCLES'simileoftheclepsydra(DK631B100)isa crucialdocumentforhistoriansofancientscience.Ithasbeen muchdiscussed,andoftenquotedinevidence,inspiteofformidabledifferencesofopinionaboutitssignificance.'Empedocles undertookanexperimentalinvestigationoftheairwebreathe' (B.Farrington).'Thestarexampleofaphysical"experiment"in thenaturalphilosophers,theclepsydra,wasnotanexperimentat all,inthepropersenseoftheword'(G.Vlastos).'AllEmpedocles didwastodrawtheexplicitinference:"thevesselcannotbe simplyempty:theairinitcannotbenothingatall".Hedidnot inventtheclepsydrainalaboratory'(F.M.Cornford).Thesimile 'hatuttoilcaratterediunaesperienzascientifica'(A.Traglia). Nowwhetherthefragmentdescribesanexperimentornot,itis certainlyasimile,andthefirststepmustbetounderstandtheforce ofthesimile.Itispossible,inmyview,thatthedifferencesof opinionaboutthefragmentspringfromvariousmisunderstandingsofthesimile;andIproposeinthisarticletoofferan explanationofitsdetailswhichIthinkisnewandwhichmay enableustoformaclearerpictureofitsplaceinthehistoryof science.
