Any attempt to write the history of a cathedral requires that the subject shall be approached with two leading ideas in view. One of these has reference to the history of a Church; the other to the story of a building. The two aspects are clearly to be distinguished, but their mutual relation may be better appreciated when we realise how intimately they are bound together. Ecclesiastical history, or "ecclesiology," and architectural history, or "archaeology," do not exist apart; for the needs of Christian liturgy indicated what arrangement was required in those buildings that were peculiarly dedicated to the use of the Church; hence we have, in the mere building itself, to consider the condition of ecclesiastical and architectural growth displayed by its character during each stage of its development, and this development, this character, is to be discovered as well in the plan and structure of the fabric, with its decorative details, as in the record that documents and traditions have preserved. But we need to remember that one see, one building, represents a link in one long continuing chain, and in doing this we naturally look back as well as forward to observe the relation of either to the past and to the present. Such an attitude as this requires that we refer to that period when the subject of this chapter was not yet part of the native soil of Sussex, and in doing this we find that so early as the eighth century the town of Chichester was even then a known centre of civil, though apparently not ecclesiastical, activity; for it is not until about the middle of the tenth century that some uncertain documentary evidence refers to "Bishop Brethelm and the brethren dwelling at Chichester." [1] It may be that Brethelm was a bishop in, though not of, Chichester, who dwelt and worked among the south Saxons living in and about the city, for the history of the diocese and see will show that probably there was no episcopate established under that name until a little more than one hundred years later. [1] Walcott, "Early Statutes," p. 12. Ceadwalla's foundation of the see at Selsea dated from about the end of the seventh century; but we know nothing about any cathedral church at that place during the following three hundred and fifty years. If, however, there was a bishop in charge of the missionary priests, deacons, and laymen who lived there together, there must necessarily have been a "cathedra" in the church they used.