1940s and 1950s, existentialism, such as that propounded by Jean-Paul Sartre, was the dominant European intellectual movement. Structuralism rose to prominence in France in the wake of existentialism, particularly in the 1960s. The initial popularity of structuralism in France led to its spread across the globe. By the early 1960s, structuralism as a movement was coming into its own and some believed that it offered a single unified approach to human life that would embrace all disciplines. Russian functional linguist Roman Jakobson was a pivotal figure in the adaptation of structural analysis to disciplines beyond linguistics, including philosophy, anthropology, and literary theory. Jakobson was a decisive influence on anthropologist Claude Lévi-Strauss, by whose work the term structuralism first appeared in reference to social sciences. Lévi-Strauss' work in turn gave rise to the structuralist movement in France, also called French structuralism, influencing the thinking of other writers, most of whom disavowed themselves as being a part of this movement. This included such writers as Louis Althusser and psychoanalyst Jacques Lacan, as well as the structural Marxism of Nicos Poulantzas. Roland Barthes and Jacques Derrida focused on how structuralism could be applied to literature. Accordingly, the so-called "Gang of Four" of structuralism is considered to be Lévi-Strauss, Lacan, Barthes, and Michel Foucault. Saussure The origins of structuralism are connected with the work of Ferdinand de Saussure on linguistics along with the linguistics of the Prague and Moscow schools. In brief, Saussure's structural linguistics propounded three related concepts. Saussure argued for a distinction between langue (an idealized abstraction of language) and parole (language as actually used in daily life). He argued that a "sign" is composed of a "signified" (signifié, i.e. an abstract concept or idea) and a "signifier" (signifiant, i.e. the perceived sound/visual image). Because different languages have different words to refer to the same objects or concepts, there is no intrinsic reason why a specific signifier is used to express a given concept or idea. It is thus "arbitrary." Signs gain their meaning from their relationships and contrasts with other signs. As he wrote, "in language, there are only differences 'without positive terms.'" Lévi-Strauss Structuralism rejected the concept of human freedom and choice, focusing instead on the way that human experience and behaviour is determined by various structures. The most important initial work on this score was Lévi-Strauss's 1949 volume The Elementary Structures of Kinship. Lévi-Strauss had known Roman Jakobson during