[Antoine Deidier, his experimental approach to the contagious nature of plague in Marseille in 1720].

Born in 1670 Deidier became a medical doctor at the age of 21. The son-in-law, of Vieussens, he took care of the inhabitants of Marseilles during the plague of 1720. A contagionist and an experimenter, he was considered as a strange scientist by his colleagues. It is time now to rehabilitate his memory.