The answer
Behind the altar lies the “cathedra,” where the bishop was seated on his throne surrounded by the priests who performed their worship and preaching; hence the use of the term presbyterum1207 for this part of the church. Above the cathedra lies the “apse” which resembles God’s bosom that is wide open to the whole world through the altar and the priestly ministry.
Fr. Tadros Yacoub Malaty
Notes
1207 John Gordon Davies, The Origin & Development of Early Christian Church Architecture (New York: Philosophical Library, 1953): p. 36; F. L. Cross & E. A. Livingstone (eds.), Oxford Dictionary of the Christian Church, 2nd ed. (Oxford University Press, 1990): p. 123.