With some expansion in detail, this book consists of lectures given in Cambridge in 1972 at the invitation of the Managers of the Maitland Memorial Fund; and it is now published with the aid of a generous grant from the Fund. To the Managers, to Mr David Yale, and to those historians and lawyers who so bravely listened, I am deeply grateful. There were power cuts at the time, and the lecturer peered from a wavering patch of candle-light much as his lectures tried to make out what sort of world lies in the darkness behind our earliest legal records. These are lights that cannot come on again; and we may never be sure of the answers to many individual questions. I shall be content if it is agreed that the questions arise, and therefore that the world cannot have been quite as we have supposed.