I have chosen to speak of Existentialism in France for two reasons. First because it is in France that Existential thinking has won its most distinguished success, both as a fashionable craze among laymen, and in the region of philosophical research. Amongst contemporary Existential thinkers, Jean-Paul Sartre and Gabriel Marcel stand out as leaders, and it is to their contrasting types of thinking that we shall pay most attention. But the second reason for confining attention mainly to French Existentialism is that there are so many other types of Existential thinking to be found in various countries. Not only France, but Denmark, Germany, Russia, Italy, Spain, and to a lesser degree America and Britain, have thinkers whose basis of thought is existentialist. And as Foulquié says: “There are as many Existentialisms as there are Existentialist philosophers”. Moreover the claim is made that Existentialist modes of thought are to be found even in Classical Philosophy. Mounier in his book Existentialist Philosophies has an interesting illustration which throws light on this history of Existentialism. He calls it “the Existential Tree”. Below the ground the several roots of this tree are labelled “Socrates”, “Stoics”, “St. Augustine” and “St. Bernard”. Where the stem emerges from the ground we find “Pascal”. The long trunk bears the name of “Kierkegaard”. At the top of the trunk, before the branches spread out, “Phenomenology” indicates that this type of philosophy is a basis of most modern Existentialist thinking. The branches are labelled with fourteen names, representing authors from various countries.