"There is a striking parallel between the spreading of germs and the spreading of ideas or propaganda. On the one hand we are dealing with a virus which can be transported and transmitted under certain conditions which favor or limit its transportation or transmission: on the other hand with ideas, religions, and doctrines, which can be described as germs, benevolent or malevolent, according to the point of view one takes up. These germs can either remain at their source and be sterile, or emerge in the spreading of infection."