Peirce is the father of semiotics. However, his theory was developed long before the developments in information theory. The codification procedures studied by the latter turn out to be crucial also for biology. At the root of both information and semiosis there are equivalence classes. In the case of biological systems, we speak of functional equivalence classes. Equivalence classes represent the grid that organism impose on biochemical processes and signals of the external or internal environment. The whole feedback circuit that (...) is built in this way allows information control. Symbolic systems represent another kind of dealing-with-information as far as they deal with the matching of our concepts with the world. (shrink)