According to the Catholic Encyclopedia, the origins of Corpus Christi can be traced to St. Juliana of Mount Cornillon.

From Pope Benedict’s General Audience from vatican.va

Dear Brothers and Sisters,

This morning too I would like to introduce a female figure to you. She is little known but the Church is deeply indebted to her, not only because of the holiness of her life but also because, with her great fervour, she contributed to the institution of one of the most important solemn Liturgies of the year: Corpus Christi.

She is St Juliana de Cornillon, also known as St Juliana of Liège. We know several facts about her life, mainly from a Biography that was probably written by a contemporary cleric; it is a collection of various testimonies of people who were directly acquainted with the Saint.

Juliana was born near Liège, Belgium between 1191 and 1192. It is important to emphasize this place because at that time the Diocese of Liège was, so to speak, a true “Eucharistic Upper Room”. Before Juliana, eminent theologians had illustrated the supreme value of the Sacrament of the Eucharist and, again in Liège, there were groups of women generously dedicated to Eucharistic worship and to fervent communion. Guided by exemplary priests, they lived together, devoting themselves to prayer and to charitable works.

Orphaned at the age of five, Juliana, together with her sister Agnes, was entrusted to the care of the Augustinian nuns at the convent and leprosarium of Mont-Cornillon.

She was taught mainly by a sister called “Sapienza” [wisdom], who was in charge of her spiritual development to the time Juliana received the religious habit and thus became an Augustinian nun.

She became so learned that she could read the words of the Church Fathers, of St Augustine and St Bernard in particular, in Latin. In addition to a keen intelligence, Juliana showed a special propensity for contemplation from the outset. She had a profound sense of Christ’s presence, which she experienced by living the Sacrament of the Eucharist especially intensely and by pausing frequently to meditate upon Jesus’ words: “And lo, I am with you always, to the close of the age” (Mt 28:20).

When Juliana was 16 she had her first vision which recurred subsequently several times during her Eucharistic adoration. Her vision presented the moon in its full splendour, crossed diametrically by a dark stripe. The Lord made her understand the meaning of what had appeared to her. The moon symbolized the life of the Church on earth, the opaque line, on the other hand, represented the absence of a liturgical feast for whose institution Juliana was asked to plead effectively: namely, a feast in which believers would be able to adore the Eucharist so as to increase in faith, to advance in the practice of the virtues and to make reparation for offences to the Most Holy Sacrament.

Juliana, who in the meantime had become Prioress of the convent, kept this revelation that had filled her heart with joy a secret for about 20 years. She then confided it to two other fervent adorers of the Eucharist, Blessed Eva, who lived as a hermit, and Isabella, who had joined her at the Monastery of Mont-Cornillon. The three women established a sort of “spiritual alliance” for the purpose of glorifying the Most Holy Sacrament.

They also chose to involve a highly regarded Priest, John of Lausanne, who was a canon of the Church of St Martin in Liège. They asked him to consult theologians and clerics on what was important to them. Their affirmative response was encouraging.

What happened to Juliana of Cornillon occurs frequently in the lives of Saints. To have confirmation that an inspiration comes from God it is always necessary to be immersed in prayer to wait patiently, to seek friendship and exchanges with other good souls and to submit all things to the judgement of the Pastors of the Church.

It was in fact Bishop Robert Torote, Liège who, after initial hesitation, accepted the proposal of Juliana and her companions and first introduced the Solemnity of Corpus Christi in his diocese. Later other Bishops following his example instituted this Feast in the territories entrusted to their pastoral care.

However, to increase their faith the Lord often asks Saints to sustain trials. This also happened to Juliana who had to bear the harsh opposition of certain members of the clergy and even of the superior on whom her monastery depended.

Of her own free will, therefore, Juliana left the Convent of Mont-Cornillon with several companions. For 10 years — from 1248 to 1258 — she stayed as a guest at various monasteries of Cistercian sisters.

She edified all with her humility, she had no words of criticism or reproach for her adversaries and continued zealously to spread Eucharistic worship.

She died at Fosses-La-Ville, Belgium, in 1258. In the cell where she lay the Blessed Sacrament was exposed and, according to her biographer’s account, Juliana died contemplating with a last effusion to love Jesus in the Eucharist whom she had always loved, honoured and adored. Jacques Pantaléon of Troyes was also won over to the good cause of the Feast of Corpus Christi during his ministry as Archdeacon in Lièges. It was he who, having become Pope with the name of Urban iv in 1264, instituted the Solemnity of Corpus Christi on the Thursday after Pentecost as a feast of precept for the universal Church.

In the Bull of its institution, entitled Transiturus de hoc mundo, (11 Aug. 1264), Pope Urban even referred discreetly to Juliana’s mystical experiences, corroborating their authenticity. He wrote: “Although the Eucharist is celebrated solemnly every day, we deem it fitting that at least once a year it be celebrated with greater honour and a solemn commemoration.

“Indeed we grasp the other things we commemorate with our spirit and our mind, but this does not mean that we obtain their real presence. On the contrary, in this sacramental commemoration of Christ, even though in a different form, Jesus Christ is present with us in his own substance. While he was about to ascend into Heaven he said ‘And lo, I am with you always, to the close of the age’ (Matthew 28:20)”.

The Pontiff made a point of setting an example by celebrating the solemnity of Corpus Christi in Orvieto, the town where he was then residing. Indeed, he ordered that the famous Corporal with the traces of the Eucharistic miracle which had occurred in Bolsena the previous year, 1263, be kept in Orvieto Cathedral — where it still is today.

While a priest was consecrating the bread and the wine he was overcome by strong doubts about the Real Presence of the Body and Blood of Christ in the sacrament of the Eucharist. A few drops of blood began miraculously to ooze from the consecrated Host, thereby confirming what our faith professes.

Urban iv asked one of the greatest theologians of history, St Thomas Aquinas — who at that time was accompanying the Pope and was in Orvieto — to compose the texts of the Liturgical Office for this great feast. They are masterpieces, still in use in the Church today, in which theology and poetry are fuse. These texts pluck at the heartstrings in an expression of praise and gratitude to the Most Holy Sacrament, while the mind, penetrating the mystery with wonder, recognizes in the Eucharist the Living and Real Presence of Jesus, of his Sacrifice of love that reconciles us with the Father, and gives us salvation.

Although after the death of Urban iv the celebration of the Feast of Corpus Christi was limited to certain regions of France, Germany, Hungary and Northern Italy, it was another Pontiff, John xxii, who in 1317 re-established it for the universal Church. Since then the Feast experienced a wonderful development and is still deeply appreciated by the Christian people.

I would like to affirm with joy that today there is a “Eucharistic springtime” in the Church: How many people pause in silence before the Tabernacle to engage in a loving conversation with Jesus! It is comforting to know that many groups of young people have rediscovered the beauty of praying in adoration before the Most Blessed Sacrament.

I am thinking, for example, of our Eucharistic adoration in Hyde Park, London. I pray that this Eucharistic “springtime” may spread increasingly in every parish and in particular in Belgium, St Juliana’s homeland.

Venerable John Paul II said in his Encyclical Ecclesia de Eucharistia: “In many places, adoration of the Blessed Sacrament is also an important daily practice and becomes an inexhaustible source of holiness. The devout participation of the faithful in the Eucharistic procession on the Solemnity of the Body and Blood of Christ is a grace from the Lord which yearly brings joy to those who take part in it. Other positive signs of Eucharistic faith and love might also be mentioned” (n. 10).

In  remembering St Juliana of Cornillon let us also renew our faith in the Real Presence of Christ in the Eucharist. As we are taught by the Compendium of the Catechism of the Catholic Church,“Jesus Christ is present in the Eucharist in a unique and incomparable way. He is present in a true, real and substantial way, with his Body and his Blood, with his Soul and his Divinity. In the Eucharist, therefore, there is present in a sacramental way, that is, under the Eucharistic Species of bread and wine, Christ whole and entire, God and Man” (n. 282).

Dear friends, fidelity to the encounter with the Christ in the Eucharist in Holy Mass on Sunday is essential for the journey of faith, but let us also seek to pay frequent visits to the Lord present in the Tabernacle! In gazing in adoration at the consecrated Host, we discover the gift of God’s love, we discover Jesus’ Passion and Cross and likewise his Resurrection. It is precisely through our gazing in adoration that the Lord draws us towards him into his mystery in order to transform us as he transforms the bread and the wine.

The Saints never failed to find strength, consolation and joy in the Eucharistic encounter. Let us repeat before the Lord present in the Most Blessed Sacrament the words of the Eucharistic hymn “Adoro te devote”: [Devoutly I adore Thee]: Make me believe ever more in you, “Draw me deeply into faith, / Into Your hope, into Your love”.

Thank you.