On Ferdinand de Saussure's Course in General Linguistics (1916) (Part I and Part II, Ch. 4), Claude Levi-Strauss's "The Structural Study of Myth" (1955), and Jacques Derrida's "Structure, Sign, and Play in the Discourse of the Human Sciences" (1966).
What is language? What is the relation between language and reality? Saussure argued that a language at a given time has a structure, where you can only really understand the meaning (or "value") of a word by contrasting it with other words. Structuralists like Levi-Strauss generalized this to all of culture, and Derrida, while rejecting the structuralist project, takes the notion of "difference" between words to uproot all meaning from any non-linguistic reality. (Probably... even our guest C. Derick Varn who's read the Derrida essay dozens of times isn't sure what it means.) Learn more about the topic and get the readings.