For some reason that I've never heard explained, living a holy life (according to Catholic and Orthodox Christian measures) sometimes has the effect of retarding the process of decay after death. I used to suspect the stories of incorruptible saints as being frauds perpetrated to advance the agenda of the Catholic Church, but as I have learned more, it has happened too many times in too many different ways for me to think that anymore. In the case of this French noblewoman, no one is trying to advance the cause of her canonization. She was found accidentally, seemingly by someone who has no interest in Catholic saints.