A distinction drawn by Peirce. A sign of a thing or state of affairs is any symptom or trace or portent of it that can be used to infer that it is present. We can make signs, so that for instance a picture on a can is a sign of its contents. Peirce described symbols as such artificial signs. But this is a mistake, for symbols are not typically used to infer the presence of what they symbolize, but to represent them in their absence, or to express intentions or to conjure up thoughts and emotions centred upon them. The theory of this difference lies at the heart of the philosophy of language.