Ut Unum Sint is the incipit

Incipit

Incipit is a Latin word meaning "it begins". The incipit of a text, such as a poem, song, or book, is the first few words of its opening line. In music, it can also refer to the opening notes of a composition. Before the development of titles, texts were often referred to by their incipits...

 of an encyclical

Encyclical

An encyclical was originally a circular letter sent to all the churches of a particular area in the ancient Catholic Church. At that time, the word could be used for a letter sent out by any bishop...

 by Pope John Paul II

Pope John Paul II

Blessed Pope John Paul II , born Karol Józef Wojtyła , reigned as Pope of the Catholic Church and Sovereign of Vatican City from 16 October 1978 until his death on 2 April 2005, at of age. His was the second-longest documented pontificate, which lasted ; only Pope Pius IX ...

 of May 25, 1995. Encyclicals are referred to by their "incipit" or first few words. The words are from the prayer of Jesus

Jesus

Jesus of Nazareth , commonly referred to as Jesus Christ or simply as Jesus or Christ, is the central figure of Christianity...

 in the Gospel according to John it deals with the Roman Catholic Church

Roman Catholic Church

The Catholic Church, also known as the Roman Catholic Church, is the world's largest Christian church, with over a billion members. Led by the Pope, it defines its mission as spreading the gospel of Jesus Christ, administering the sacraments and exercising charity...

's relations with the Orthodox Church and other Christian ecclesial communities. This document reiterated that unity of these two sui juris churches is essential, as well as further dialogue and unity with the Protestant churches. This document shows that the Roman Catholic Church is officially moved to unity. It has become a common piece of study in ecumenical classes.

In paragraph 54, we find the oft-quoted sentence: "In this perspective an expression which I have frequently employed finds its deepest meaning: the Church must breathe with her two lungs!" In paragraph 79, we see five subjects that are considered important for "more clear" understanding that will bring unity:

• The relationship between Sacred Scripture, as the highest authority in matters of faith, and Sacred Tradition
  Sacred Tradition
  Sacred Tradition or Holy Tradition is a theological term used in some Christian traditions, primarily in the Roman Catholic, Anglican, Eastern Orthodox and Oriental Orthodox traditions, to refer to the fundamental basis of church authority....
  
  , as indispensable to the interpretation of the Word of God;
• The Eucharist
  Eucharist
  The Eucharist , also called Holy Communion, the Sacrament of the Altar, the Blessed Sacrament, the Lord's Supper, and other names, is a Christian sacrament or ordinance...
  
  , as the Sacrament
  Sacrament
  A sacrament is a sacred rite recognized as of particular importance and significance. There are various views on the existence and meaning of such rites.-General definitions and terms:...
  
   of the Body and Blood of Christ, an offering of praise to the Father, the sacrificial memorial and Real Presence
  Real Presence
  Real Presence is a term used in various Christian traditions to express belief that in the Eucharist, Jesus Christ is really present in what was previously just bread and wine, and not merely present in symbol, a figure of speech , or by his power .Not all Christian traditions accept this dogma...
  
   of Christ
  Christ
  Christ is the English term for the Greek meaning "the anointed one". It is a translation of the Hebrew , usually transliterated into English as Messiah or Mashiach...
  
   and the sanctifying outpouring of the Holy Spirit
  Holy Spirit
  Holy Spirit is a term introduced in English translations of the Hebrew Bible, but understood differently in the main Abrahamic religions.While the general concept of a "Spirit" that permeates the cosmos has been used in various religions Holy Spirit is a term introduced in English translations of...
  
  ;
• Ordination
  Ordination
  In general religious use, ordination is the process by which individuals are consecrated, that is, set apart as clergy to perform various religious rites and ceremonies. The process and ceremonies of ordination itself varies by religion and denomination. One who is in preparation for, or who is...
  
  , as a Sacrament, to the threefold ministry of the episcopate, presbyterate and diaconate;
• The Magisterium
  Magisterium
  In the Catholic Church the Magisterium is the teaching authority of the Church. This authority is understood to be embodied in the episcopacy, which is the aggregation of the current bishops of the Church in union with the Pope, led by the Bishop of Rome , who has authority over the bishops,...
  
   of the Church, entrusted to the Pope
  Pope
  The Pope is the Bishop of Rome, a position that makes him the leader of the worldwide Catholic Church . In the Catholic Church, the Pope is regarded as the successor of Saint Peter, the Apostle...
  
   and the Bishops in communion with him, understood as a responsibility and an authority exercised in the name of Christ for teaching and safeguarding the faith;
• The Virgin Mary, as Mother of God and Icon
  Icon
  An icon is a religious work of art, most commonly a painting, from Eastern Christianity and in certain Eastern Catholic churches...
  
  of the Church, the spiritual Mother who intercedes for Christ's disciples and for all humanity.