The Polish Count Alfred Korzybski, born in 1879, was the originator of the aphorism, "The Map is Not the Territory," widely invoked in service of the proposition that we have no direct, unmediated contact with the external world, or with Reality (which is commonly considered the same thing). The territory, in this aphorism, is the world and the map is the web of generalizations which we use to make sense of it. (Gregory Bateson was one to fruitfully employ Korzybski's aphorism.)
Korzybski work in General Semantics, as he called his discipline, was aimed at dealing with the problems due to, what he saw as, faulty thinking exacerbated by the unreflective way we use language. His appreciation of the benefits of language, which he saw as differentiating us from other animals and as being responsible for the accomplishments of human culture, was tempered by an equal appreciation of the harm it could do. He had lived through the further reaches of this harm in the First World War (during which time he moved to North America).
An enthusiast for the scientific method and mathematical description, Korzybski wanted to bring these to bear on everyday human behavior. In addition, he developed a training program designed to teach people how to use language, which may sound like a quixotic pursuit, but might better be considered a training in how to think. Because we generalize from our experience we are able to pass on knowledge to others, even to other generations. But, of course, generalizations are summaries of, that is, abstractions from, a much larger body of experience. In living from these generalizations we can lose touch with the concrete experiences of our day to day lives. While our experiences might share many similarities, those which are picked out in generalizations, they are also each, individually, different one from another. To the extent we lose sight of the unique texture of every moment of ongoing experience, our life migrates into an abstract realm where we easily find ourselves caught up in the twists and turns of tangled skeins of thought. And that can hurt. As Billy Name once said, "Thought is a mean dragon."
As a corrective, Korzybski advocated a number of methods to tie thinking down to clear referents and to reveal the levels of abstraction in play (the descriptions we give of our descriptions, the feelings we have about our feelings, and the thoughts we have about the thoughts we've had, etc.). One illustration he was fond of using in his lectures was to point to a chair and announce, "This is not a chair." That party-piece must have been a bit of a brain-stopper in the Thirties. His intent was to bring home that the word "chair" is not something we sit upon. (Rene Magritte's painting showing a pipe and, written beneath, the words "This is not a pipe" [he also painted a French version] makes the same point, with the added fillip that the pipe itself is not a real object but a painting.)
Science and Sanity: An Introduction to Non-Aristotelian Systems and General Semantics, 1933, fifth edition, 1994.
Collected Writings: 1920-1950. Edited by M. Kendig. 1990.