The prophecy of Isaiah is not in the book of the twelve prophets, who are called the minor from the brevity of their writings, as compared with those who are called the greater prophets because they published larger volumes. Isaiah belongs to the latter, yet I connect him with the two above named, because he prophesied at the same time. Isaiah, then, together with his rebukes of wickedness, precepts of righteousness, and predictions of evil, also prophesied much more than the rest about Christ and the Church, that is, about the King and that city which he founded; so that some say he should be called an evangelist rather than a prophet. But, in order to finish this work, I quote only one out of many in this place. Speaking in the person of the Father, he says, “Behold, my servant shall understand, and shall be exalted and glorified very much. As many shall be astonished at Thee.” This is about Christ.
But let us now hear what follows about the Church. He says, “Rejoice, O barren, thou that barest not; break forth and cry, thou that didst not travail with child: for many more are the children of the desolate than of her that has an husband.” But these must suffice; and some things in them ought to be expounded; yet I think those parts sufficient which are so plain that even enemies must be compelled against their will to understand them.
Reproduced in full. Translation: Nicene and Post-Nicene Fathers, series 1, vol. 2 (Schaff, 1887), public domain (Public domain).