From the Catechism of the Catholic Church
1718 The Beatitudes respond to the natural desire for happiness.  This desire is of divine origin: God has placed it in the human heart (the desire for happiness) in order to draw man to the One who alone can fulfill this desire:

We all want to live happily; in the whole human race there is no one who does not assent to this proposition, even before it is full articulated.  How is it then that I seek you, Lord? Since in seeking you my God, I seek a happy life, let me seek you so that my soul may live, for my body draws life from my soul and my soul draws life from you.  

God alone satisfies.

1719 The Beatitudes reveal the goal of human existence, the ultimate end of human acts: God calls us to his own beatitude.  This vocation is addressed to each individual personally but also to the Church as a whole.

1723 The Beatitudes confront us with decisive choices concerning earthly goods; they purify our hearts in order to teach us to love God above all things.  They teach us that true happiness is not found in riches or well-being, in human fame or power, or in any human achievement–however beneficial it may be—such as science, technology and art or indeed in any creature, but in God alone the source of every good and of all love.

1724  The Decalogue, the Sermon on the Mount, and the apostolic catechesis describe for us the paths that lead to the Kingdom of heaven.  Sustained by the grace of the Holy Spirit, we treat them step by step by everyday acts.  By the working of te Word of Christ, we slowly bear fruit in the Church to the glory of God.