A text is meaningful because it is an actualisation of the potential that constitutes the linguistic system; it is for this reason that the study of discourse (‘text linguistics’) cannot properly be separated from the study of the grammar that lies behind it.
Relations of internal cause — cause in the sense of ‘x so I think/say y’ — are construed metaphorically by verbs of proving such as prove, show, demonstrate, argue, suggest, indicate, imply in ‘intensive identifying relational’ clauses.
The stratification of the content plane had immense significance in the evolution of the human species — it is not an exaggeration to say that it turned Homo … into Homo sapiens. It opened up the power of language and in so doing created the modern human brain.
