37 And no one can doubt that the Church is a virgin, who also in the Epistle to the Corinthians is espoused and presented as a chaste virgin to Christ. So in the first Epistle he gives his counsel, and esteems the gift of virginity as good, since it is not disturbed by any troubles of the present time, nor polluted by any of its defilements, nor shaken by any storms; in the later Epistle he brings a spouse to Christ, because he is able to certify the virginity of the Church in the purity of that people.
Source: Letters (New Advent)