Andreas of Caesarea — on Rev 1:4 (COMMENTARY ON THE APOCALYPSE 1:4)

“Although there are many churches in every place, he wrote to seven only. For through the number seven he indicates the mystery of the church which exists everywhere and that which corresponds to the present life in which there is a sevenfold period of days. And therefore he makes mention of seven angels and seven churches to which he says, "Grace to you and peace from the tri-hypostatic deity." Through the phrase "who is" the Father is indicated, who spoke to Moses: "I am Who I am." Through the phrase "who was" the Word is indicated, who was in the beginning with God. And through the phrase "who is to come" the Paraclete is indicated, who always visits the children of the church in holy baptism but will come more perfectly and more clearly in the age to come. It is possible to recognize in the seven spirits the seven angels who have received the governance of the churches. These are not numbered with the most divine and royal Trinity but are mentioned together with it as servants, even as the divine apostle says: "I testify to you before God and the elect angels." These phrases may be understood also in another manner. The phrase "who is and who was and who is to come" may signify the Father, who encompasses in himself the beginning, the middle and the end of all things.”