The Pentecost dome mosaic’s golden surface, in the eleventh-century monastery church of Hosios Loukas in Phokis, crowns the actual liturgical space before the apse, in front of the altar. Peter and Paul face each other at the east, across a gap; behind them the Apostles sit in a circling row, speaking to one another in pairs. The axial division, aligned with the Virgin in the apse holding the divine Child, draws attention to her. This architectural arrangement of the imagery unites the sacramental and human aspects of the salvation that the Pentecost miracle enabled the Apostles to preach (Acts 2:14ff).
Above each Apostle’s halo a ray containing a flame descends from a representation of the Trinity in heaven’s blue disk at the centre of the dome. The dove of the Spirit, facing Mary, perches over the Word, in the form of a golden book, on the throne of the Father. The individual red tongues, like candle flames, hover upright as if sliding down the tapered rays.
Although the Apostles are un-named, and without distinguishing attributes apart from the bound volumes or scrolls representing the Word they would spread, their depictions follow portrait types already established in Byzantium.
Paul’s presence expands the subject here to the authoritative teaching of the faith, beyond a historical event isolated in time; he was not yet a follower of Christ at the time of the Pentecostal gathering described in Acts 3. Yet he would become paired with Peter as an apostolic leader; Paul’s letters to widespread Christian communities explain the need for them to join in proclaiming the faith as God’s word speaking through his people.
There is also a reminder, in the centring of the throne between Peter and Paul, of the orthodoxy established by the Ecumenical Councils. In Byzantine depictions the council delegates sit on either side of the Patriarchal throne in a curved group, just like the Apostles seated at Pentecost.