The customs of a community, taken as a whole, always have a particular style and are reducible to systems. I am of the opinion that the number of such systems is not unlimited and that—in their games, dreams or wild imaginings—human societies, like individuals, never create absolutely, but merely choose certain combinations from an ideal repertoire that it should be possible to define. By making an inventory of all recorded customs, of all those imagined in myths or suggested in children's games or adult games, or in the dreams of healthy or sick individuals or in psycho-pathological behaviour, one could arrive at a sort of table, like that of the chemical elements, in which all actual or hypothetical customs would be grouped in families, so that one could see at a glance which customs a particular society had in fact adopted.