Hence the name of triumphal arch was given to the vast space in front of the High altar.

It may also be remarked that a railing or screen marks the limits of these two parts of the cathedral.

Saint Gregory Nazianzen regards this as the border line traced between the two parts--that of God, and that of man.
"There is, however, a different explanation given by Richard de Saint Victor, as to the sanctuary, the choir, and the nave.

According to him, the first symbolizes the Virgins, the second the chaste souls, and the third the married hearts.

As to the altar, or, as old liturgical writers call it, the _Cancel_ (chancel), it is Christ Himself, the spot whereon His Head rests, the Table of the Last Supper, the Stake whereon He shed His blood, the Sepulchre that held His body; and again, it is the Spiritual Church, and its four angles the four corners of the earth over which it shall reign.
"Now behind this altar we find the apse, assuming in most cathedrals the form of a semicircle.