In order that the several classes of persons attending church might be kept strictly within those portions of the building which were assigned to them, a special order of door-keepers existed in the Church. The keys of the church were solemnly delivered to these _ostiarii_, and they were accounted to form the lowest in rank of the minor orders. The simple words of the commission, uttered by the bishop to the _ostiarius_, were, "Behave thyself as one that must give an account to God of the things that are kept under these keys." Such was the formula prescribed by the fourth Council of Carthage (398 A.D.), and found in the Roman ritual of the eighth century. This order of clergy was almost confined to the west, however; we find traces of its existence at one time at Constantinople, but for the most part the deacons guarded the men's entrance, and sub-deacons or deaconesses the women's, in the east. [Illustration: WEST DOOR, HOLY TRINITY, COLCHESTER.] In the earliest English churches the entrance was of a very simple nature; for the artistic skill of the people was small, and their ideals were unambitious. The buildings consisted of a nave without clerestory, and a chancel; the door being placed in the centre of the western wall. A curious example of such a door meets us at Holy Trinity, Colchester, although in this case it gives admittance not into the nave directly, but through the ancient tower. This tower, the oldest part of the church, has been constructed of the fragments of buildings older still; the Roman bricks of the ruined city of Camulodunum having been used to form it. In the western side is a narrow doorway, contained by two square shafts with very simple capitals, and having a triangular head with an equally simple moulding by way of drip-stone. The date is supposed to be between 800 and 1000 A.D. A church perhaps yet older is that of S. Lawrence at Bradford-on-Avon, which has a good claim to be the veritable structure reared by S. Aldhelm in the first years of the eighth century. Here there is a northern porch of unusual size in proportion to the rest of the building; the entrance to which is by means of an arched doorway, tall and narrow. The narrowness of some of these ancient doorways is remarkable. At Sowerford-Keynes is one, now built up, which, though nearly nine feet high, is but 1 foot 9 inches wide at the springing of the arch, widening towards the base to 2 feet 51/2 inches. The jambs are of "short and long" work, and the abacus has a very simple zig-zag moulding. The arch itself is not built up, but carved out of one stone, which is cut square on the upper side and scooped into a parabolic curve on the lower. A double row of cable moulding decorates it. This, which has been called "one of the most characteristic specimens of Saxon architecture in England," was the northern entrance to the church. Another instance of a western door of simple design is supplied by Crowle, or Croule, in north Lincolnshire.