the importance of signs and signification has been recognized throughout much of the history of philosophy, and in psychology as well. the term derives from the greek: σημειωτικός, "sēmeiōtikos", "observant of signs" (from σημεῖον "sēmeion", "a sign, a mark"). for the greeks, "signs" occurred in the world of nature, and "symbols" in the world of culture. as such, plato and aristotle explored the relationship between signs and the world.