1 This paper is written in the memory of Mademoiselle Sarrade and Robert Haulotte. As usual, this paper has been corrected — gently and diligently — by Miss Anna Dunlop to who I am infinitely indebted. Nil novi sub sole: as Cardan said, speaking of Pacioli, “Without him, my own work would not be what it is”. I can say, speaking of Miss Dunlop, “Without her, my own work could not be what it is.”
