The book Nefesh Hachaim
The book is based on the Zohar, Etz Chaim, and other books of Kabbalah, the book comes to explain issues in the world of Judaism, and was written as a response to the Chabad Hasidic book of the Tanya.

Gate 1 - The man
The main idea of Gate 1 - states according to the Torah and Kabbalah, that man was created in the image of God, therefore just as God's name expresses God's control and lordship over the entire universe [the possessor of all powers], so man includes in his pattern all the forces and the worlds, and therefore he has the powers of the universe to influence for good or for bad the entire universe, from its hidden top to its visible bottom, with all the visible and hidden worlds in it, and even to add power in the entourage of a top and to increase the divine revelation in the world in secret - give strength to God, and he rides heaven with your help. And in this regard, he is superior to the angels, and man does not need mediators between him and God, also because in every deed man can realistically affect all the universes, one must be careful and meticulous in one's actions, as the Torah, which is the soul of the world, guides them.
Gate 2 - The prayer
Although there is an unfathomable and infinite gap between the essence of the infinite Creator and man, and it is boldness to turn to Him, he discovered that this is His will.
The worship of God in the heart is prayer, and it is the spiritual food for the worlds and for man himself, and therefore it stands in the glory of the world. The blessing we bless God is not for the infinite essence of God, for it is closed from everything and we have no perception of it, but for the essence of infinity on the part of God's powers that connect to the world through our knowledge and understanding, in this man's prayer awakens God's abundance to descend and revive everything, and this is the matter of blessing, abundance and the multiplication of divine vitality in the world.
When a person prays, he must not pray to the revelations of God, but to the only one of the worlds, to the essence of God alone. In our reading to him - to him and not to his measurements [sefirot]. The intention of the prayer should be to add strength in the upper worlds.
Gate 3 - God
God is the place of the world and the world is not its place, that is why it is called the MAKOM [place], and therefore at every moment all the worlds come into being and exist by His will, He is called by the name of God, because He connects with the worlds by His will, creates them and sustains them in every moment, God's relation to the world is as the soul is for the body, like an empty space. God fills everything - I fill the heavens and the earth, and His essence are in everything.
End to Gate 3
Warning haste in God's service.
Gate 4 - Torah study
Studying the Talmud and the commentaries is of great importance. The main thing is understanding the things, and not admiration and emotional attachment, the Torah is God's speech, the light of all the worlds, existence and the root of everything, and the world was created for the Torah that arose in the first thought. Everyone who studies Torah adheres to the speech of God who created all the worlds and founded the earth, and became a partner in the act of creation.
The root of the Torah above the world of nobility - Israel ascended with first thought. Everyone who studies Torah adds divine vitality, noble light and abundance in all the worlds, all of which illuminate and rejoice in this revelation, until that noble animality reaches him to purify, sanctify and complete him, and transfer him to miraculous leadership.