Auxiliaries are one of the most complex areas of English syntax. Disagreement over both the principles and details of their grammar has been substantial. Anthony Warner here offers a detailed account of both their synchronic and diachronic properties. He first argues that lexical properties are central to their grammar, which is relatively non-abstract. He then traces in detail the history of processes of grammaticalisation in their development and claims most notably that we can identify a group of auxiliaries in English from an early period on formal, not just semantic, grounds. This book...