I read a book about naturism "Le Bonheur d'être nu. Le Naturisme, un art de vivre" by France Guillain.
Here is the summary that is on the back and translated by google stranlate : "Millions of French and Europeans frequent the naturist places regularly. Would all these people be dangerous depraved? No ! Giving the body its proper place, discover the pleasure of living in harmony with nature, this is the truth of naturism, far from the stereotypes and fantasies. For this practice, which nudism is only one component, is based on a philosophy of life promoting tolerance, respect for self, others and the environment.
By opening the doors naturist places, by sharing the mode of existence of the families who have chosen to enjoy simple yet challenging joys, France Guillain, sailor, journalist and writer, but especially naturist long, invites us better know this issue activity of an ancient tradition and the deep motivations of men and women looking through this lifestyle naked, not a form of marginality, but the well-being, happiness and freedom."
https://www.amazon.fr/Bonheur-d%C3%AAtre-nu-Naturisme-vivre/dp/2226093540