394. Now because this was foreseen and provision was made that the human race should not perish in eternal death, it is here said that 'nobody should do violence to Cain', who means separated faith. It is also said that a sign was put on him', that is, the Lord distinguished faith in a special way to ensure its preservation. These points are arcana which have not yet been disclosed. They are what the Lord meant in Matthew when He spoke about marriage and about eunuchs,

There are eunuchs who were born so from their mother's womb, and there are eunuchs who have been made eunuchs by men, and there are eunuchs who have made themselves eunuchs for the sake of the kingdom of God. He who is able to receive this let him receive it. Matthew 19:12.

People with whom the heavenly marriage exists are called 'eunuchs'. 'Eunuchs born from the womb' are like celestial angels, 'those made so by men' are like spiritual angels, 'those who have made themselves eunuchs' are like angelic spirits, who are moved not so much by charity as by obedience.