In the preceding lectures, we have seen that there is a set of functional domains of language which provide the source for notions and operations to be grammaticalized. These are subdomains of cognition and communication that are so central to human life that they appear regularly in language, so they are both available and useful for grammaticalization. However, the grammaticalized notions are not the ones that provide the content of messages; this is provided by lexicalized notions. The grammaticalized notions just contribute to the task of structuring the message. Therefore it is of lesser importance which of the functional domains a language selects for grammaticalization.

This last lecture is devoted to a particular aspect of the cognitive basis of grammaticalization, viz. the change from linguistic operations that the speaker has full control of to linguistic processes which run automatically.