After being born in the village of Retinnes (then part of the Holy Roman Empire) in 1192, Saint Juliana and her twin sister Agnes were left as orphans at the young age of five. The twins were placed in the care of the nuns at the hospice at Mont-Cornillon, a hospice very close to the town of Liege. They both worked at a small farm outside the hospice as they grew. Agnes tragically passed away sometime between 5 and 13 (no official records list her exact year of death) leaving Saint Juliana alone. After joining the order at 13, Saint Juliana began to work in it's leprosarium and spent much of her free time in adoration in front of the Eucharist. As a child her reputation for having a great veneration for the Eucharist was well known and she longed for a feast day to be dedicated specifically to it.
At the age of 16, Saint Juliana had a vision that would forever change her life. In the vision, she saw the moon, bright and full, crossed diametrically by a dark black stripe. She believed the moon symbolized Church on earth and the dark line representing the absence of a feast dedicated to the body and blood of Jesus Christ. She entrusted this vision only to the Blessed Eve of Liege and a few trusted sisters in the monastery but otherwise kept it to herself as she had no way of influencing the creation of a feast at this time.
In 1255, Saint Juliana was elected prioress of the double canonry. This election filled her with more self-confidence and she soon confided the visions to her confessor, Canon John of Lausanne. Canon John, with her permission, shared the vision and her intent on a feast with several leading French theologians, including Bishop Robert de Thorete and Archdeacon Pantaleon of Troyes (who would later be Pope Urban IV). These theologians joined together in agreement that the feast would not break any tradition or doctrine of the Catholic church and endorsed the idea together. Together with Canon John, Saint Juliana composed the initial version of the office, Animarum cibus. It was initially instituted in Bishop Robert's diocese but he died shortly after work began on the implementation and was unfortunately not able to see it fully celebrated.
As prioress, Saint Juliana found herself in the middle of a growing and intense culture war. An emerging middle class began to demand new rights, political rivalries took new life and quarrels among the lower nobility all converged to cause a powder keg of cultural friction and the emergence of lesser self discipline. She re-instated the strict Augustinian rules back into the convent to combat these but was met with intense pushback. In 1240, the canonry came under the supervision of an evil man named Rodger (who had gained this position through ill-gotten ways). Rodger strongly disagreed with the strict rule Saint Juliana instituted and immediately began a campaign to see her ousted. He accused her of diverting and ultimately stealing funds meant for the hospital. She fled and was taken in at the home of her dear friend and confessor Canon John. After a brief return when Rodger was dismissed from his position she was again forced to leave when Rodger regained his role on the death of Bishop Robert. She fled to the Cistercian Abbey of Salzinnes before living a solitary life at Fosses-la-Ville.
Saint Juliana died on April 5, 1258 and upon her wishes the Cistercian monk Gobert d'Aspremont moved her body to Villers Abbey.
1261, the Archdeacon Panteleon of Tours, a friend and embracer of the feast she had for seen in her visions, was elected Pope. Taking the name Pope Urban IV, he instituted the Solemnity of Corpus Christi as a feast for the entire Roman Catholic church via the papal bull Transiturus de hoc mundo. He tasked Saint Thomas Aquinas, then the chief theologian, to compose an office for the Feast of Corpus Christi. A copy was sent to Saint Juliana's friend, Dame the recluse Eve of Saint Martin and the two are considered some of the very first women authors of medieval Europe.
Saint Juliana was formally canonized by Pope Pius IX in 1869. Saint Pope John Paul II wrote a letter commemorating her on the 750th anniversary of the Feast of Corpus Christi. Today her feast day is celebrated on April 6th.