What is the central theme of the passage?

Directions: Read the following passage and answer the question that follows.

It is no antiquarian pedantry that traces the origin of parliament back to Saxon times. For the tradition that the king must govern with the advice of his great men was already well established when the Conqueror arrived, and his Great Council not only included men who had been of the Council of Edward the Confessor, but was rightly regarded by Englishmen as the constitutional equivalent of  the witena gemot.
Feudalism was basically a system of land tenure by which the freeman held land from his lord in return for certain services – military and other – and the lord in his turn owed service to the king as overlord. But it was much more than a system of land tenure. Feudalism was a whole way of life – a social system in which lord and vassal were bound together by the closest possible ties. In the oath of homage the vassal swore ‘to become your man for the tenement I hold of you and to bear faith to you of life and members and earthly honours against all other men. The effect of this relationship was to bring into being a community of tenants with the lord at its centre. This community found its concrete expression in the honorial court, to which the tenants were bound to come and wherein the lord was entitled to their advice. When, therefore, we are told, the Conqueror asserted his lordship over every acre of the land, he thereby brought into being a single feudal community, the honour of England, His vassals, alias tenants-in-chief, alias barons, as members of this feudal community, owed duty of attendance and advice in the royal court.
Royal courts were held thrice a year on the solemn occasions at Christmas, Easter and Whitsun when the Normal kings wore their crowns. The chronicler tells us that there were present ‘all great men of England, archbishops, bishops, earls, thegns and knights.’ It is well known that from the earliest times a special notification of summons was sent to each tenant-in-chief and there were penalties for non-attendance. At these courts pleas were judged and decisions taken on matters of state. The tradition of these great courts at the crown-wearings was never quite lost. A hundred years later, in 1176, Henry II held his Christmas court at Nottingham and immediately afterwards held a great council with bishops, earls and barons of the kingdom, at which various great business was done; and when, in the middle of the next century (in 1258), the barons at Oxford demanded three parliaments a year they were harking back to the old thrice-yearly crown-wearing courts.
In the intervals between these great national assemblies, and for the ordinary business of government, the king relied upon a small number of personal advisers. These advisers were the members of the royal household and essentially, therefore, royal servants. In the Norman and Angevin periods, these household officers were normally drawn from the ranks of the baronage, but with the growing complexity of administration, several of the most important offices, notably those of the chancellor, the treasurer and the justices, came to be held by officials – men of non-baronial rank with professional qualifications. At the same time, this little group of personal advisers began to acquire an organisation of its own and we can speak of a ‘council’ rather than of ‘counsellors’. (British Parliament)