When drawing close to the Promised Land, the holy patriarch Moses, being inspired by God, saw that the people would desire a kingly ruler. He therefore laid out rules for them, as is found in Deuteronomy:
You shall surely set a ruler over you whom the Lord your God chooses; one from among your brethren you shall set as a ruler over yourself; you cannot set a foreigner over yourself, because he is not your brother. (17:15)
What does such a commandment have to do with those of us who live thousands of years after this was spoken? Everything, for it was ultimately portraying the image of Christ as our ruler.
Since the fall of mankind, the proper authority and hierarchy has been usurped by the passions. These serve as foreign rulers over each one of us. The Apostle Paul laments our condition when he writes to the Romans,
For we know that the law is spiritual, but I am carnal, sold under sin. For what I am doing, I do not understand. For what I will to do, that I do not practice; but what I hate, that I do. (7:14-15)
The proper hierarchy is for the body to be in submission to the soul (mind, will, emotions), the soul to the spirit (the higher, eternal part of us), and the spirit to God. That is how we were created to exist, and in such a state, we find deep, lasting peace and bliss. 
However, we are enslaved by an inverted order. The body with its desires for pleasures and comforts, drives us insatiably from one pursuit to another; the soul with its egoism and self-worship, either brings division or unifies with impure motivations. The spirit within us, unable to endure the usurpation of its rule, stings us through the conscience or attempts to inspire us toward God with fleeting moments of spiritual bliss or insight. In the former instance, the result is that the man is miserable because he is enslaved to the passions and his spirit will not leave him alone (“but what I hate, that I do“). Such an unhappy state is, in some ways, good. It means the spirit is still alive in man, it has not gone completely dormant, he is still capable of movement toward salvation. He has a godly restlessness and may continue to seek fulfillment in the passions, but God allows it so that he will see how empty it is and, in turn, seek the One who is deeper than all the world has to offer.
WHEN THE KING RULES WITHIN
Various signs of a proper authority and hierarchy are given in the passage of Deuteronomy quoted above,
[The ruler] shall not multiply a cavalry for himself. (17:16), meaning those who are ruled by Christ reject honor, power, and prestige from the world, or at least are not attached to a position that has been given to them. Additionally, they will not use whatever authority they have to dominate others nor attempt to grasp more authority and power than what God has allowed them.
[He shall not] cause the people to return to Egypt (17:16), meaning when our Lord rules within us we will not return to old ways of sin or sources of fleshly comfort. In our culture where every sort of rich food is available, pleasures are immediate, and luxuriant comfort easy to obtain, it is difficult to overcome the flesh, which pushes us back toward the familiar enslavement of Egypt. By this commandment, though, we can discern where a thought is coming from when it attempts to entice, lure, or justify a return to Egypt. Temptations will come for all, even the saints, but through Christ we can overcome, For the law of the Spirit of life in Christ Jesus has made me free from the law of sin and death. (Rom 8:2).
Neither shall he [the ruler] multiply wives for himself, lest his heart be changed (17:17), meaning that a man ruled by Christ will have internal unity, a singular mind. He will not be “wed” to various pursuits and distractions in life that take him away from his First Love, and change his heart — that was once on fire for Christ — to be lukewarm. While a layman will have various hobbies and activities in his life, none of these take the place of serving Christ or his Church. Such a man finds peace because he is not pulled in multiple directions simultaneously by various “lovers.”
Nor shall he greatly multiply silver and gold for himself (17:17), meaning that those who are ruled by Christ do not seek riches or worldly “stuff.” Having possessions is not a sin; Abraham himself was a wealthy man. But seeking to “greatly multiply” our wealth or possessions is evidence of a heart ruled by foreign passions.
[He shall make a copy of the scriptures and] it shall be with him, and he shall read it all the days of his life, that he may learn to fear the Lord his God and be careful to observe all these commandments and ordinances, that his heart may not be lifted above his brethren, that he may not turn aside from the commandment to the right hand or to the left… (17:18-20) Those who seek to have Christ reign within them will diligently study the scriptures so that their minds may be purified and that they may be enlightened in how to live a life pleasing to God. Such a person will have humility, and even in his heart, will “not be lifted above his brethren.” In part, that means that he will turn to the church in order to understand the scriptures, for he will recognize he is not more intelligent, clever, or godly than those brethren who have come before him. He needs the collected wisdom of the church to understand scripture and to live properly. His life will also display balance in which he follows the commandments of God, and understanding the spirit of how to apply these things, he will turn aside neither “to the right hand” of legalistic strictness nor “to the left” of laxity and frequent exceptions.
I find it fascinating that the command is made that the kingly ruler be “one from among your brethren,” that is, one of us. In the incarnation of Christ, our God pitched his tent among us (John 1:14) and became fully man while retaining his full divinity as well. Doing so, he not only become our brother in the flesh, but his divinity touching our humanity brought life back to it and made us capable of receiving his divine Spirit to dwell within us. Through the power of the Holy Spirit, he provides the means to the perfection to which we are called (Deut. 18:13 & Matt. 5:58), in addition to the example of his own life.
Glory to God who does not leave us as enslaved captives to the foreign passions, but comes to us as king, brother, and God, providing the means of salvation through his grace dwelling in us!
 The exact definitions of “soul” and “spirit” have varied from author to author over the ages. My usage here, and the hierarchy expressed, comes from a recollection of my readings in St. Theophan the Recluse’s The Spiritual Life. I don’t have access to a copy of the book (it’s packed since we are getting ready to move), so I apologize if I have not recalled everything accurately.