Ambrose of Milan : For he who is baptized is seen to be purified both according to the law and according to the gospel. According to the law, because Moses sprinkled the blood of the lamb with a bunch of hyssop. According to the gospel, because Christ's garments were white as snow, when in the gospel he showed forth the glory of his resurrection. — On the Mysteries 7.34 Augustine of Hippo : They are to bear in mind that those who celebrated the Passover at the time through figures and shadows, when they were commanded to mark their doorpost with the blood of the lamb, marked them with hyssop. This is a mild and humble plant, but it has very strong and penetrating roots. So, "being rooted and grounded in love," we may be able "to comprehend with all the saints what is the breadth and length and height and depth," that is, the cross of the Lord. — ON CHRISTIAN TEACHING 2.41.62 Gregory of Nazianzus : Be it so, some will say, in the case of those who ask for baptism; what have you to say about those who are still children and conscious neither of the loss nor of the grace? Are we to baptize them too? Certainly, if any danger presses. For it is better that they should be unconsciously sanctified than that they should depart unsealed and uninitiated.A proof of this is found in the circumcision on the eighth day, which was a sort of typical seal. It was conferred on children before they had use of reason. And so is the anointing of the doorposts, which preserved the firstborn, though applied to things which had no consciousness. — ORATION 40.28