Like Strachey’s Dr Arnold, Louis Pasteur was all ‘energy, earnestness and the best intentions’. The anti-clerical Third Republic made him its principal intercessor with the invisible world. It erected an absurdly baroque shrine to his memory at the Institut Pasteur and named more streets after him than after any other historical figure, save that Republic’s founder, Gambetta. Somehow, though, the reducing lens of irony seems inadequate to bring Pasteur into clear view. If anything still frightens us, it is disease, and Pasteur, though at times an insufferable prig, was also, as the 19th century could say more easily than we can, a benefactor of humankind. Countless wall plaques, popular images and milk cartons remind us that he was not only the promulgator of the germ theory but also the man who conquered fowl cholera and anthrax, as well as a disease called pebrine that left silkworms looking as though they had been sprinkled with pepper and cost the French silk industry millions of francs annually, and the ‘maladies of wine’ (one of which, by causing good claret to spoil in the bottle, threatened to deprive France of some of the benefits of a recent commercial treaty with England). And he became world-famous of course as the vanquisher of rabies, an age-old scourge that killed few but terrified many.
This centennial year of Pasteur’s death has produced a spate of new books, among them a splendid biography by Patrice Debré, an Aids researcher and professor, fittingly at the Institut Pasteur; a concise life by Pierre Darmon, a historian of medicine; and a detailed examination, based on laboratory notebooks, of certain aspects of Pasteur’s research, by Gerald Geison, who is a historian of science at Princeton. Debré’s study is now the best one-volume introduction to both the man and his work, replacing René Dubos’s Louis Pasteur, franc-tireur de la science (1955) and the hopelessly hagiographic Vie de Pasteur (1900) by the scientist’s son-in-law, René Vallery-Radot. Debré is admirably lucid about the scientific problems that Pasteur confronted and equally impressive in surveying the cultural landscape; Darmon is purposeful and brisk; Geison’s book is essentially a series of specialised papers cobbled together and spiced with much-publicised allegations of scientific fraud.
What kind of man was Pasteur? First of all, he was famously myopic. When no microscope was to hand, he had to put his face very close to his work. One story has him dropping onto all fours in a pasture to discover the means by which the anthrax bacillus travelled from the dead to the living: via the earthworm, whose excrement carried the germ. He was also famously taciturn. On the anniversary of her wedding, Mme Pasteur wrote to her daughter: ‘Your father, very busy as always, says little to me, sleeps little, and gets up at dawn – in a word, continues the life that I began with him 35 years ago today.’ One of his assistants called him a ‘secretive worker, who kept his ideas and projects to himself ... He kept us at such a distance from his thinking that we couldn’t account for his anxieties.’ Nothing was permitted to interfere with his research. When his son’s mother-in-law threatened to visit Paris, Pasteur did not mince words: ‘I beg you to consider, dear Madam, that the state of my health demands the greatest consideration and that you make me the unhappiest of men when I see you coming to Paris for a stay that you say at first will last only a few days but that I know will inevitably stretch into several weeks. This will put me in an extremely grumpy mood.’
Pasteur’s remarkable social ascent became a paradigm for the French system of national education. His great-grandfather had been almost literally a serf. His father, a tanner, had served under Napoleon and reared young Louis in the cult of the Emperor. In maturity Pasteur continued to honour the imperial virtues – authoritarian order and utilitarian science – as the midwives of modernity: campaigning for the Senate from his native Jura in 1876, he told voters that ‘while politics with its senseless divisions saps our strength and fills our enemies with joy, steam, the telegraph, and countless other miracles are transforming the world,’ and he promised that, if elected, he would represent ‘Science in all its purity’. When the voters preferred a candidate who put their own interests above those of science, Pasteur found another outlet for his nationalist passion: he patented a process for making beer that he hoped would allow France to surpass the superior brewing skills of ‘those scoundrelly Germans’. The new brew was to be marketed as the ‘Beer of Revenge’.
If Pasteur’s imperiousness doomed his political ambitions under the Republic, his humourless inflexibility had already complicated his academic career under the Empire. As an administrator at the École Normale, he conducted searches of the students’ rooms and punished those found with contraband literature: Rabelais, Goethe’s Werther, Michelet’s Sorcière. And he precipitated a government crisis when he expelled a student who had written an injudicious letter to Sainte-Beuve. The furore subsided only when Pasteur was sacked, but as a consolation prize Napoleon the Small ordered that a laboratory in ‘physiological chemistry’ be created for him at the École.
This was yet another instance of Pasteur’s uncanny luck. ‘Chance favours the prepared mind,’ he said, but clearly it also favoured the blundering if well-connected martinet. He came by his connections honestly enough: the Emperor, a kindly, intermittently intelligent despot, took a benevolent interest in science, and in Pasteur’s work on optical isomers and the problems of brewers in particular – the same two areas that attract Gerald Geison, whose book is concerned with what he calls Pasteur’s ‘private science’.
This Geison defines as ‘those scientific activities, techniques, practices and thoughts that take place more or less “behind the scenes” ’. What he means is that, for some years now, he has been able to study 144 ‘holographic notebooks’ that Pasteur’s grandson donated to the Bibliothèque Nationale in 1964. Pasteur was particularly possessive about these records. In 1878 he told his family never to show them to anyone. Geison’s premise is that the ‘discrepancies’ between private records and published accounts can reveal important truths about the process of discovery and the nature of scientific knowledge. He warns us that such ‘formulaic discrepancies’ should not be taken as evidence of deliberate deception. Rather, the massaging of data and polishing of results found in scientific papers are intended ‘to provide an efficient and authoritative public presentation of the most pertinent results to an expert audience with little need of elaborate additional detail’.
In Pasteur’s case, Geison finds a further reason for attending to the private side of science: Pasteur’s ‘carefully orchestrated public performances invite a close examination of the private dress rehearsals’. Indeed, Bruno Latour, in his much-controverted Pasteurisation of France, went so far as to say that ‘Pasteur’s genius was in what might be called the theatre of proof.’ Geison, though less inclined to iconoclasm than Latour, nevertheless chooses to construct his book around episodes in Pasteur’s long career in which the scientist’s genius for theatricality was crucial.
Pasteur performed at first on a modest stage. His report of a remarkable discovery concerning the interaction of certain crystals with light drew the attention of the eminent scientist Jean-Baptiste Biot, who, in the spring of 1848, just as Paris was caught up in yet another revolution, summoned the young researcher to the Collège de France to examine his claim that he could take a solution of paratartaric acid, which has no effect on polarised light, and from it produce crystals of two kinds, chemical ‘isomers’, one of which would rotate the plane of polarisation to the left, the other to the right. This optical asymmetry was linked, moreover, to a physical asymmetry in the crystals themselves. What Pasteur had found, in short, was the fons et origo of modern biochemistry. He later recounted how he was obliged to carry out the crucial experiment ‘before [Biot’s] very eyes’ – quite literally a theatrical proof. What do the notebooks reveal? That before he arrived at his discovery, Pasteur was confused about what he was looking for. That he was guided in his search by the work of Auguste Laurent, whom he later wrote out of the record possibly for self-interested reasons. That, when he presented his results publicly, he expressed the clarity of his mature understanding rather than the confused path that had led him there. And that we should therefore be sceptical of scientists’ accounts of their own work.
Pasteur himself would scarcely have been surprised by this. He had thought a good deal about the teaching of science and had a lively appreciation of the issues that matter to the historian, ‘I know,’ he wrote in a passage quoted by Debré,
that most scientific discoveries can be stated in a few words and that their demonstration calls for only a small number of decisive experiments. But if one tries to discover their origins, if one rigorously traces their development, one sees how slowly those discoveries emerged. Hence one can adopt two methods for expounding them. One is to state a law and promptly demonstrate it ... The other, more historical, is to recall the individual efforts of the principal inventors.
The classical concision of Pasteur’s demonstration won Biot’s crucial support for his research. Pasteur now hungered after success on a wider stage. Debré speculates that it was the loss of two daughters to typhoid fever that drove him to ‘seek, even more than the esteem of his peers, that of the public’. A debate over spontaneous generation gave him his opening. The naturalist Félix Pouchet (who had studied medicine under Dr Achille-Cléophas Flaubert, the novelist’s father) had propounded a theory of ‘heterogenesis’, according to which, as Geison summarises it, life is the result of a ‘mysterious and unknowable “plastic force” ’ that produces ‘not adult organisms ... but rather their eggs’. Pouchet, a Protestant, held that his theory was perfectly compatible with religion: ‘the laws of heterogenesis, far from weakening the attributes of the Creator, can only augment the Divine Majesty.’ His cause was taken up by the positivists, however, who saw heterogenesis as offering a purely chemical understanding of the origin of life.
Clearly this was a debate that had the makings of a cause célèbre, and Pasteur did not shrink from the challenge. He devised a remarkable series of experiments to make his case against heterogenesis, which was not without gaps, as Pouchet and his supporters repeatedly pointed out. Beyond the experiments, Pasteur also devised, for a command performance at the Sorbonne before Princess Mathilde and other VIPs, an equally remarkable staging of his argument, which ‘made dramatic use of light and darkness, beams, shades and shadows’ and of ‘tangible “props” such as ... swan-necked flasks, bubbling chemicals, metallic tubes etc’. Geison, who has previously judged Pasteur rather harshly, now deems his official victory – duly proclaimed by a (thoroughly biased) panel of hand-picked academicians – justifiable if not spotless: Pasteur was not only the ‘more ingenious and more skilful experimentalist’ but also the ‘more effective rhetorician’.
Geison’s account is rather narrowly focused, however. He makes a general case that Pasteur rejected the possibility of spontaneous generation because of his commitment, alluded to in the notebooks, to an ‘asymmetric cosmic force’ in all organic processes. No doubt it pleased him to think that his work on crystals and his later work on living organisms were thus profoundly linked. But he also delighted in his ingenuity as an experimenter and relished exposing the flaws in his rivals’ techniques. ‘Attack my experiments,’ he challenged his critics. ‘Prove that they are incorrect instead of trying new ones that are merely variants of mine, but into which you introduce errors that then have to be pointed out to you.’ Moreover, Geison is so intent on the performer that he neglects the audience at the Sorbonne, whose composition is equally instructive. Among those in attendance was an influential official well disposed to Pasteur, Victor Duruy, the Minister of Public Instruction and architect of an ambitious programme of educational reform that met with strenuous clerical opposition. Geison is not wrong to argue that, in opposing spontaneous generation, Pasteur took the orthodox Catholic side of the question, but he did so in a manner that made it clear, as liberal Catholics like Montalembert had been doing for some years, that the time had come for God and science to divide the territory here below. As Pasteur put it, ‘in each of us there are two men, the scientist and the man of faith or doubt. The two domains are distinct, and woe unto him who seeks to make the one encroach on the other in the current imperfect state of our knowledge.’
Like Duruy, who helped to keep his career on track, Pasteur was a conservative reformer, not the obscurantist reactionary, the ‘latterday Paracelsus’, for whom Pouchet mistook him. As such, he was in many ways an ally of the positivists whom he so doggedly opposed: both wished to circumscribe the intellectual authority of religion. They largely agreed about the kinds of question that science could and should adjudicate; about the rest they differed only as to whether one should or shouldn’t remain silent. In Pasteur’s reception speech at the Académie Française, he was obliged to offer a eulogy of his predecessor, the arch-positivist lexicographer Littré. A preliminary draft included a venomous sentence not present in the final version: ‘I must recount for you the life of a freethinker whose independence consisted in a self-imposed duty not to think at all about certain subjects.’ This judgment can be applied to Pasteur himself: he drew a firm line between religion and science, declared the two compatible, and imposed a duty on himself not to question this settled understanding.
Pasteur knew, moreover, that science, like religion, could endure only if it built itself a suitable tabernacle. He chose his words carefully in a letter to Napoleon III: ‘This research, which corresponds in my mind to the great act by which organic matter is transformed after death and to the obligatory return of everything that has lived on the earth or in the atmosphere, is compatible only with the establishment of a vast and rich laboratory.’ Experience had taught him that ‘vast and rich’ laboratories came to those who impressed the public with the incontrovertibility and utility of their results. And what was more incontrovertible than death? What more useful than life? So when challenged to demonstrate the effectiveness of his anthrax vaccine at a farm in the village of Pouilly-le-Fort, he accepted. The agreed protocol stipulated that 25 sheep were to be inoculated with a vaccine prepared in Pasteur’s laboratory and that another 25 were to be left unvaccinated. All were then injected with the anthrax bacillus. Pasteur’s prophecy that the vaccinated would live and the others die was duly confirmed, and at this demonstration of human power over life and death the sceptics were converted: one veterinarian who had gone so far as to agitate the tubes containing the lethal serum (in case Pasteur injected some sheep from the top of the liquid and others from the bottom) even proposed to inoculate himself with the most virulent strain of anthrax – after immunisation with Pasteur’s vaccine.
Geison, however, is much less ardent. The tell-tale notebooks reveal the ‘secret of Pouilly-le-Fort’: namely, that Pasteur used a vaccine prepared not by himself but by his assistant Chamberland, who had attenuated the anthrax with potassium bichromate rather than by Pasteur’s method of exposure to oxygen. Pasteur never actually said he had used an oxygen-attenuated vaccine: he merely implied it, and did so in part because his commitment to a vitalist (anti-heterogenist) philosophy had led him to question the work of a rival, Jean-Joseph Toussaint, who had attempted to produce a vaccine by exposing the anthrax bacillus to carbolic acid. Such a vaccine, containing only the chemical residue of dead bacilli, would have contradicted Pasteur’s understanding of immunity. As it turned out, Toussaint’s vaccine didn’t work, Pasteur’s understanding of immunity was incorrect, he later did produce an oxygen-attenuated vaccine, and Chamberland’s method of attenuation had borrowed from Toussaint’s approach, albeit using a different chemical agent and to a different end. Should we be grateful that we now have the event in all its richly dispiriting confusion, or peeved that the stark dramatic contrast between the bleating survivors and the lifeless animals in the next pen has been spoiled by so much harsh new light?
Geison turns again to the notebooks when he goes on to rabies, a disease that was not only invariably fatal, but reduced to a sliver the boundary between reason and madness, or man and animal. It is not without irony that Joseph Meister, whose recovery made Pasteur world-famous, committed suicide after being obliged by Nazi invaders to open Pasteur’s mausoleum, where he was employed as a guard: madness bit the poor man twice. From the notebooks Geison finds that Pasteur was not entirely candid about his experiments on human subjects. For one thing, he had previously tried a rabies vaccine on two patients, a man named Girard, who recovered but may not have had rabies, and a girl named Julie-Antoinette Poughon, who died. For another, Pasteur ‘had never tried, not even once, to cure symptomatic rabies in animals by any method before he decided to treat Girard’. He began animal experiments a few days later, but ‘the animal died three days after the first series of injections.’
Was Pasteur reckless? Geison thinks so. He sees a ‘headlong and headstrong quest for vaccines’ in which Pasteur, continually experimenting with new recipes for preparing treatments from the dried spinal cords of rabbits, was always ready to try the latest formulation on a human patient even though it had yet to be tested on animals. Clearly the knowledge that rabies was always fatal eased his scruples, but the disease was notoriously difficult to diagnose. Apparently Pasteur was among those awed by his own stunning demonstrations of power over life and death, and he developed a remarkably robust faith that he could do no harm. When, in an incident that Geison omits, Dr Grancher, one of his assistants, accidentally stuck himself with a syringe filled with a virulent emulsion, Pasteur proposed that he inoculate himself with the rabies vaccine and then, as if to conjure away any possible doubt about the wisdom of this procedure, offered to receive the first injection himself. Grancher, while more than willing to risk his own life, refused to jeopardise Pasteur’s. Pasteur then ordered his nephew, Adrien Loir, to inoculate him. Loir refused but offered to submit to inoculation himself. Finally, Loir inoculated Grancher, whereupon Grancher treated Loir and a third assistant, while Pasteur looked on. It is hard to read this episode as anything other than a ritual of expiation: for all their profession of faith in science, these were men anxious about tampering with the deepest mysteries. Geison evidently feels that their behaviour needs to be measured against a later standard of medical and scientific ethics; I doubt that such a retrospective arraignment has much to teach us.
When Pasteur was laid to rest in one of those grandiose state funerals at which the French excel, Edmond de Goncourt remarked that ‘the honours bestowed on great men – Pasteurs though they may be – are, I think, becoming a bit excessive; they may have inherited too much of what used to belong to God.’ In this legacy there was consolation of a sort for God’s death: witness the astonishing pseudo-religious symbolism of the Pasteur mausoleum, its pendentives adorned with symmetrical images of the fluttering angels Charity and Science, its walls decorated with hagiographic scenes of Pasteur among the dogs and chickens. Religion and science, the twin realms that Pasteur had delineated with such serene certitude, had all but coalesced under the not disinterested patronage of the state. Now that science, too, has become the object of withering scepticism, what consolation remains?