"It is important to understand what I mean by semiosis . All dynamic action, or action of brute force, physical or psychical, either takes place between two subjects, whether they react equally upon each other, or one is agent and the other patient, entirely or partially, or at any rate is a resultant of such actions between pairs. But by "semiosis" I mean, on the contrary, an action, or influence, which is, or involves, a cooperation of three subjects, such as a sign, its object, and its interpretant, this tri-relative influence not being in any way resolvable into actions between pairs."

-- Charles Sanders Peirce

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