The documents of the time are rare. These three centuries are the crucible of Europe, and record is drowned and burnt in them. Our study of their social conditions, especially in the latter part, are matter rather of inference than of direct evidence. But the sale and purchase of men, already exceptional at the beginning of this period, is almost unknown before the end of it. Apart from domestic slaves within the household, slavery in the old sense which Pagan antiquity gave that institution had been transformed out of all knowledge, and when, with the eleventh century, the true Middle Ages begin to spring from the soil of the Dark Ages, and a new civilisation to arise, though the old word _servus_ (the Latin for a slave) is still used for the man who works the soil, his status in the now increasing number of documents which we can consult is wholly changed; we can certainly no longer translate the word by the English word _slave_; we are compelled to translate it by a new word with very different connotations: the word _serf_. The Serf of the early Middle Ages, of the eleventh and early twelfth centuries, of the Crusades and the Norman Conquest, is already nearly a peasant. He is indeed bound in legal theory to the soil upon which he was born. In social practice, all that is required of him is that his family should till its quota of servile land, and that the dues to the lord shall not fail from absence of labour. That duty fulfilled, it is easy and common for members of the serf-class to enter the professions and the Church, or to go wild; to become men practically free in the growing industries of the towns. With every passing generation the ancient servile conception of the labourer's status grows more and more dim, and the Courts and the practice of society treat him more and more as a man strictly bound to certain dues and to certain periodical labour within his industrial unit, but in all other respects free. As the civilisation of the Middle Ages develops, as wealth increases and the arts progressively flourish, this character of freedom becomes more marked. In spite of attempts in time of scarcity (as after a plague) to insist upon the old rights to compulsory labour, the habit of commuting these rights for money-payments and dues has grown too strong to be resisted.