Song of Solomon 7:5

"The hair of your head like purple, a king caught in its tresses." Your hair was previously loose and hence was compared with the flocks of goats emerging in Gilead, whereas now it is caught up, and not only caught up but also wondrously dyed, resembling a king clad in purple and hastening in all directions. By the comparison of her fastened hair to royal purple he refers to the teaching proposed in orderly fashion and colored with the blood of Christ. A king clad in purple is not so resplendent as the teacher of religion who carefully composes the proclamation of the knowledge of God and offers it to the devotees of truth.

Your head is like Carmel, etc. In the head of the bride, the soul of the faithful is rightly understood, because just as the members are ruled by the head, so are thoughts arranged by the mind. Hence, even the thoughts themselves, which emerge countless times every hour and moment from the human mind, are aptly depicted as hair. What is said about one chosen soul is to be understood by the prudent reader as applying to the whole Church, because even though the multitude of believers differs in merits, they nevertheless have one heart and soul, insofar as they all aspire to the heavenly courts with one and the same faith, hope, and love. Scripture recounts that Elijah prayed on Mount Carmel kneeling, and after a long drought, he obtained rains from the Lord. Thus, the head of the bride is like Carmel, because the hearts of the chosen are elevated through their way of life and provide an ascent to the Lord through their daily progress in virtues. For Elijah is called the Lord God, who prays to the Father in them and, like dry fields, calls rains from heaven because he invisibly ignites them to pray to God, and through their prayers and merits, he often grants his gifts to a world in peril. The name of Carmel, which is interpreted as the knowledge of circumcision, fits the head of the bride, that is, the ecclesiastical mind, which well knows it should not boast in carnal but in spiritual circumcision, about which the Apostle also debates much to the Galatians, and the prophet teaches, saying, "Circumcise yourselves to the Lord, and take away the foreskins of your heart" (Jer. IV). The Jews refused to have this knowledge when they only glorified in the outward circumcision. Therefore, they did not know to have their head like Carmel because their mind was set on things below and on the glory of the flesh. Hence, they rightly deserve to be reproached by the voice of the blessed proto-martyr Stephen, saying, "You stiff-necked people, uncircumcised in heart and ears, you always resist the Holy Spirit" (Acts VII). And he says, "The hair of your head is like a purple rope bound in channels." The hair of the bride's head, as we said, represents the thoughts of the faithful soul. But the purple signifies the imitation of the Lord's passion, to which the hair of the bride's head is rightly compared, because every thought of the chosen ones is fortified by the holy…