This monograph presents the first comprehensive diachronic account of copular and passive verb constructions in Old and Middle English. Peter Petre analyzes:

- The mysterious loss of the high-frequency verb weoroan 'become' as a casualty of changing word order in narrative during Middle English.
- The merger of is 'is' and bio 'shall be, is generally' into a single suppletive verb, and how it is related to the development of a general analytic future shall be.
- The co-occurrence of multiple changes that led to become and wax crossing a threshold of similarity with existing...