Selection and combination are the two elementary operations in constructing a complex object systematically. Elements selected bear a relation of similarity to each other; elements combined bear a relation of contiguity to each other.

These are also the two elementary semiotic operations in the construction of messages from a sign system. Interlocutors

• select a linguistic unit from a category
• combine units into a complex unit.

In speech, these operations take place simultaneously at different hierarchical levels. In saying Tom, I select the phoneme /ɒ/ instead of /i/, combining it with /t/ and /m/. At the same time, I select Tom instead of Tim or Peter; and so forth upwards the complexity hierarchy of linguistic units.