The brilliant moralist and essayist Plutarch (born AD 49 and thus his life overlapped with St Paul who died around 65/66 AD) raised an issue concerning a good ruler – which was also a concern of Paul: the law written on the heart. But they came to rather different conclusions on the matter:

Who then shall have power to govern a prince? The law, without doubt; which (as Pindar saith) is the king of mortal and immortal beings; which is not written without in books nor engraven on wood or stone, but is a clear reason imprinted in the heart, always residing and watching therein, and never suffering the mind to be without government. The king of Persia indeed commanded one of his lords that lay in the same chamber to attend him every morning, and to sound these words in his ears: Arise, O king! and take care of those affairs and duties that Oromasdes requires of thee. But a wise and prudent. prince hath such a monitor within his breast as always prompts and admonishes him to the same effect.

The law on the heart is a peculiar attribute of a good ruler. The law restrains the prince: it is knowledge which governs the governor. If the knowledge is present will effectively direct reason.

Paul raises the same issue of the law written on the heart in his letter to the Roman Church:

12 For all who have sinned without the law will also perish without the law, and all who have sinned under the law will be judged by the law.

13 For it is not the hearers of the law who are righteous before God, but the doers of the law who will be justified.

14 For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law.

15 They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them

16 on that day when, according to my gospel, God judges the secrets of men by Christ Jesus.

Rom2.12-16

The law is present upon every heart. But the law does exactly govern although it does judge. The law sets up as tribunal and gives a judgment. This judgment of the law proves the law has been written on every human heart. It also acts a warning of the greater judgment to come.

This law is different than Plutarch’s version because it belongs to all – but more importantly it gives judgment but does not convey the power to conform:

19 Now we know that whatever the law says it speaks to those who are under the law, so that every mouth may be stopped, and the whole world may be held accountable to God.

20 For by works of the law no human being will be justified in his sight, since through the law comes knowledge of sin.

Rom3.19-20

This perhaps demonstrates the fundamental similarity and distinction between a worthy moralist such as Plutarch and Paul.

In the Bible the fault is far deeper than knowledge. Reason also does not restrain desire; and twisted desire brings madness:

And since they did not see fit to acknowledge God, God gave them up to a debased mind to do what ought not to be done.

Rom1.28

The prophet Jeremiah in a vivid section describes sin against known law so:

23 How can you say, ‘I am not unclean, I have not gone after the Baals’? Look at your way in the valley; know what you have done- a restless young camel running here and there,

24 a wild donkey used to the wilderness, in her heat sniffing the wind! Who can restrain her lust? None who seek her need weary themselves; in her month they will find her.

Jer2.23-24

And so the Christian can not rely upon education alone because the fault is worse than ignorance.

I think history demonstrates that even the wisest rulers have made spectacularly poor decisions when driven by foolish desire. And thus the judgment for depth of treatment and accuracy of human nature go to Paul.