Halliday & Matthiessen (1999: 24):
In general the process of creating meaning involves constructing some kind of lexicogrammatical generalisation — some form of wording that is in some respect unique. It is not possible to quantify the degree to which any semantic feature or domain has been codified at any one moment in semohistory; but meanings that are more highly codified are those that have been to a greater extent condensed and/or compacted, where 'compacting' is generalising on the syntagmatic axis (e.g. animal that has four legs > quadruped), while 'condensing' is generalising on the paradigmatic axis (forming into a system at some point along the scale of delicacy). The evolution of language (i.e. of specific languages in their various registers), the learning of language by children, and the production of language in the form of discourse constitute the historical contexts in which meanings are continuously being created along these lines.