During millennia, the mechanisms of procreation have constituted for man an unfathomable and irritating riddle. In the sixteenth century, mystery remained still untouched upon and Montaigne complained about it. The author assigns a place to his communication within the celebrations held this year to commemorate the fourth centenary of the writer's death. In the seventeenth century, De Graaf will establish the identity of ovarian follicles and Van Leeuwenhoek will discover spermatozoons, prominent strides, but their functions will remain mysterious. In the eighteenth century, Spallanzani will demonstrate the semen's fertility, but without linking the former discoveries. In the nineteenth century only, the mechanisms of fertilization will tell their secret, when the necessity of the union of the two gametes, indispensable condition so that the egg can divide by bipartition and give birth to an embryo which will have the double heredity of origin, will be shown up.