Louis Pasteur (1822-1895) in 1886.

On this Parisian Spring day in 1879, the seats in the Academie de medecine amphitheatre are full.  On the stage, a most esteemed medical practitioner is disserting with eloquence on the causes, in his opinion, of puerperal fever, that infectious illness which declares itself after a birth.  The epidemic has been ravaging maternity for years, killing a great number of women, despite the care with which they are surrounded.  Suddenly, a man of average height, bearded, wearing a false collar and a bow-tie, energetically interrupts him from where he is sitting:

“What is causing the epidemic has got nothing to do with all that!  It’s the doctor and his personnel who transport the microbe from a sick woman to a healthy one.”

When the surgeon replies that he greatly fears that this microbe will never be found, the man descends from the audience, dashes to the blackboard, draws an organism in the form of a string of seeds and says in a loud voice:

“There, that’s what it looks like!”

This man is Louis Pasteur.  He had taken the microbe, that he has just drawn, from sick people and had observed it under his microscope.


Seven years earlier, in 1873, when the sounds of the war with Prussia and those of the barricades of the Commune were fading away in Paris, the arrogant Academie had reluctantly admitted this new free associate into its select club, electing him by a very slight majority, and he wasn’t even a doctor.  Even if his work has distinguished him as a top-ranking scholar.  This chemist, whom a good number of medical practitioners present in the audience dream of “sending back to his test-tubes”, descends into this assembly as if he is descending into an arena, and draws the sword of his deep, powerful voice with the Princes of Science, as doctors call themselves at this epoch.

This man would write one of the most interesting chapters in the History of Civilization, that of the saving of millions of human lives, without ever having studied Medicine.  He will forever remain “the man who made death retreat”.


Listen to him expounding inside this Academie‘s amphitheatre, barely a few months after his election, answering a contradictor:

“You have no opinion on spontaneous generation my dear colleague, I have no trouble believing you, while at the same time, I deplore it.  You say that in the state of Science at the moment, it is wiser not to have an opinion.  Well, I have one!  Because I have acquired the right to have one through twenty years of hard work, and it would be wise for all impartial minds to share it!”

Murmurs of approbation mount from the highest rows in the audience, those of the students.

“My opinion, even better, my conviction, is that spontaneous generation is a chimera!  There is no life on Earth without similar anterior life, without parents!  And it should be impossible for you to contradict me, for my experiments are all standing, and all prove that spontaneous generation is a chimera!  Illness is not spontaneous in us, of us, through us…”

Stalking around the tribunal dragging his leg, an already distant souvenir of a cerebral haemorrhage, he weighs up the learned assembly and suddenly becomes inflamed:

“To resume, what do you want, partisans of spontaneous generation or complacent or unconscious supporters of this doctrine?  Attack my experiments, prove that they are inexact instead of constantly doing new ones that are only variations of mine, but where you introduce errors that then have to be pointed out to you!”

He adjusts his spectacles in front of his myopic eyes and continues, hammering out his words:

“The infinitely small, that’s what we need to research, those subtle artisans of a lot of disorder inside the living economy.  Let me remind you here of the words of one of your most illustrious colleagues who is no longer with us, the Surgeon Velpeau:  ‘A pinprick is a door open to death.’  Therefore, harness yourselves to pursuing the destruction of these infinitely tiny beings, prevent their penetration into the human body, such is the programme that you must follow!”


Spontaneous generation.  That was the great business that had been occupying Louis Pasteur for the last seventeen years, against which he had been fighting with his incredible work ethic, every day of his life, with his test-tubes, his microscope, his eloquence and his unshakeable faith in Science.

The theory of spontaneous generation was the one according to which living creatures could appear “spontaneously” on the surface of the planet, without pre-existing parents, like worms which, it had been thought since Antiquity, appeared spontaneously in an apple, in meat, or on a dead animal.  In the XVIIth Century, Van Helmont gave a famous recipe for “making” mice:  you just had to place in a pot a dirty shirt, grains of wheat and a piece of cheese, and mice “spontaneously” appeared one day.  Later on, a less naive Italian, a Professor of Medicine in Padua, Vallisneri, recognized that the worms in fruit came from an egg laid by an insect before the fruit developed, and that this egg produced a worm.  The theory of spontaneous generation then began to lose ground but, paradoxically, the apparition of the microscope at the end of the XVIIth Century gave it back all its vigour.  Where did these thousands of organized beings that could now be seen on glass slides under the copper instrument’s lense come from?  And the infinitely small beings which appeared in rain water as well as in all of the infusions of organic matter which were exposed to air?

If spontaneous generation is possible, nothing prevents the interpretation of the germs found in the sick as being the product of this generation in blood or humours.  In other words, illness surges spontaneously in the sick, who engender it themselves.  The holders of this theory will call themselves the “heterogenists”.  The Dutchman Van Leeuwenhoek, pointing a microscope for the first time on an infusion of hay, discovers some “infusories”, then the Irish priest John Needham sees “spontaneous” germs in a phial closed by a cork containing heated mutton juice.  But the Italian Abbot Spallanzani retorts that the Irishman hadn’t heated the air enough and that the porous cork had let in “animalcules” from the outside…

To be continued.