In his commentary on Aristotle’s Nicomachean Ethics St Thomas discusses the degree to which certain elements in criminal, private and public law are demanded by natural law or are indifferent matters to be determined by the human legislator.

1030. Then, at ‘Those things that are,” he shows how the legally just are changeable without exception. He says that regulations that are just according to arrangement and advantage, i.e., by what is agreed among men for some utility, are similar to measures of salable commodities, wine and wheat. These are greater where products are bought wholesale but smaller where products are sold retail. So also things that are not naturally just but fixed by men are not the same everywhere, thus the same punishment is not inflicted everywhere for theft. The reason is that civil life and the administration of the state are not the same everywhere. All laws are framed as they are needed for the end of the state, although only one form of government is everywhere best according to nature.

One very striking thing about St Thomas’s own answer to the question of that one form of government everywhere best according to nature is that he never mentions hereditary monarchy. He certainly favours (mixed) monarchy but, in the De Regno, he envisages the monarch as elected by the people and removable by them.

49 If to provide itself with a king belongs to the right of a given multitude, it is not unjust that the king be deposed or have his power restricted by that same multitude if, becoming a tyrant, he abuses the royal power. It must not be thought that such a multitude is acting unfaithfully in deposing the tyrant, even though it had previously subjected itself to him in perpetuity, because he himself has deserved that the covenant with his subjects should not be kept, since, in ruling the multitude, he did not act faithfully as the office of a king demands.

He also considers the question of a ruler who is set over the multitude by a higher authority to whom one may have appeal in the case of tyranny. This would be the case for all rulers of the Christian people for St Thomas because each must be subject to the Roman Pontiff ‘as to our Lord Jesus Christ Himself’. Finally, he considers the case when “no human aid whatsoever against a tyrant be forthcoming” and tells us “recourse must be had to God”.

All of this seemed to be entirely convincing. I have often reflected on the unwillingness of Samuel that the Israelites should accept a king and God’s reply to his prayer “Hearken to the voice of the people in all that they say to you; for they have not rejected you, but they have rejected me from being king over them.” This problem is resolved by the assumption of human nature by the Lord Himself through the flesh of Mary of David’s line (Romans 1:3). We have returned to era of Judges where God is our King and He is served on earth by non-hereditary magistrates.

One obvious reason for this is that the King must be the one who is able to bring the multitude to their end. Originally man was created in such a way that sanctifying grace would be transmitted along with nature by descent from Adam, but this is no longer the case. Now we are born children of wrath and must be reborn in the Church from the font.

One of the objections St Cyril Apostle of the Slavs (baptismal name: Constantine) received when on his mission to the Khazars is that the Christians do not observe the principle of heredity in their government (the Emperor Michael III had recently been deposed by Basil I, a circus strong man).

Why do you follow the evil custom of replacing one Emperor with another of a different lineage? We do this only according to lineage. The Philosopher [St Cyril] said to him: “Yet in place of Saul, who did nothing to please Him, God chose David, who was pleasing to Him, and David’s lineage.”

When St Cyril reaches the ruler of the Khazars they wish to determine where to place him and he most eloquently rejects any idea that he should be ranked by his noble birth.

When Constantine came for the feast at the Kagan’s and they wished to seat him, they questioned him, saying: what is your station so that we may seat you according to your rank?” And he said: “I had a great and very renowned forefather who stood close to the Emperor. But he voluntarily rejected the great honour granted to him and was banished. He became impoverished after going to a foreign land and there he begot me. Though I have sought my forefather’s former station, I have not succeeded in obtaining it, for I am Adam’s scion.” They then said: “O guest, you speak worthily and rightly.” And from that moment they began to confer honour upon him.

St Cyril goes on to have an even more remarkable conversation when the Jewish missionaries who are competing with him for the Khasars’ souls claim that the Lord cannot be the Messiah because all agree that the fourth monarchy in Daniel 7 is Rome and that the Messiah’s monarchy will succeed this and yet St Cyril is a Roman. The Ιsapóstolos replies that those called Romans now are not Romans in the same  sense as the Pagans who have perished they are the Kingdom of the Messiah.

The one thing that always concerned me about this robust Christian Republican doctrine was the analogy of the priesthood. We have priests even though Christ is the one true priest, why not kings even though Christ is the one true king? But then it occurred to me that there is a clear correspondence between the prophetic, priestly and kingly offices of the plebs Christiana and the religious, the clergy and the laity. Thus the public office of King is perpetuated in the  Christian people through the authority of fathers. Of course, in St Cyril’s own Byzantine rite a key element in the sacrament of marriage is the crowning of the spouses.

It is said that Herod Agrippa was processing through Jerusalem one day when his entourage threatened to collide with an intersecting bridal procession. Herod Agrippa told his procession to stop and wait for the bride to pass for he was king every day while she was only a queen on that day. Perhaps he was wrong.