Rebbe Nachman taught: A person's heart contains two inclinations: one towards good and one towards evil. This causes division within the heart. An example of this division is when a person feels he "knows" that G-d is always present, yet is lax in using his prayer time to really speak to G-d. If he truly felt G-d's presence, he would certainly pray with all his might. The fact that he is lax and does not exert himself to pray with full concentration shows that part of him "does not acknowledge" G-d's presence. This is the result of a "divided" heart. [Likutey Moharan I 62:2]
Strife, simply defined, is a lack of accord between two parties. Two countries might argue between themselves, so might two families or two individuals. The strife that exists within one's own heart is the result of a schism between one's right side, which strives for spirituality, and one's left side, which pulls towards materialism. Someone who has not yet succeeded in fully purifying his heart will always feel this "inner strife". Questions of faith, and confusion concerning both one's immediate and longterm goals are all symptomatic of a divided heart.
Rebbe Nachman explained it this way: The world is full of strife. There are wars between the great world powers, there are conflicts within different localities, there are feuds among families, there is discord between neighbours and friction within a household, between man and wife, between parents and children... Life is short; people die a little each day. The day that just passed will never return, but people still fight, and never once do they remember their ultimate goal in life.
The characteristic traits of each nation are reflected in individuals. Some nations are known for their anger, for example, and others for bloodthirstiness. Each nation has its own particular trait. In the same way, these traits are to be found in each household. Even someone who wishes to live in peace can be dragged into conflict by virtue of his living among conflicting parties.
Man is a microcosm, holding within himself the world and everything in it. A man living alone can become insane, because his personality is forced to focus upon the "warring nations" within him, and he finds no peace. When Moshiach comes, all these wars will be abolished.
If someone's heart is divided, what can he do to "pull himself together"?
Rebbe Nachman placed much emphasis on the study of the Codes of Law. The Codes abound with discussions, sometimes quite heated, between the various Sages regarding what is permitted and what is forbidden, what is pure and what is impure, and so on. One's goal during one's studies should be to clarify the opinions of the Sages, bringing "peace" to the opposing views and coming to a clear conclusion. This method of study - examining opposing views and arriving at a peaceful solution - can have a deep and lasting effect upon a person's character. Employing one's Binah (understanding) to resolve a conflict of Torah Law can bring "peace" to one's divided heart, the heart divided between two inclinations.
Though this method of study is an advanced one and will certainly pose difficulties for those who are unfamiliar with the system of Talmudic research, Rebbe Nachman's directive to study the Codes in order to achieve lasting benefit is a universal one. In several lessons, he speaks about the importance of studying and knowing the Codes in order to proceed on the proper path in life.
Rebbe Nachman taught further: The good inclination is known as "a poor but wise child" [Ecclesiasties 4:13] - poor because few listen to him, wise because he leads one on the path of life. The evil inclination is compared to "an old foolish king" - people tend to listen because he is king, but his advice is foolish. These two inclinations represent the kingdom of holiness and the kingdom of impurity. One who studies Torah with effort strengthens the kingdom of holiness. [Likutey Moharan I 1:2]
The Arizal used to expend tremendous effort in his studies of the Codes. He exerted himself so much that it caused him to break out in a sweat.
Rebbe Nachman teaches that advice which comes from improper sources overwhelms the heart and putrefies it. The heart is then compared to an outhouse; the advice of that heart is malodorous. Rabbi Chaim Vital thus writes that the reason the Arizal worked himself into a sweat when he studied was in order to break the illusory powers of the evil inclination that envelop the heart. We know that excess waste products pollute one's system and we know that sweating is one way of purifying the body of this waste. The 613 commandments of the Torah are called the "613 precepts of advice". This type of advice also brings harmony to the heart, clearing it of division.
Source: "Anatomy of the Soul" by Chaim Kramer