In 1246, Bishop Robert de Thorete of the diocese of Liège, at the suggestion of St. Juliana of Mont Cornillon (also in Belgium), convened a synod and instituted the celebration of the feast. From Liège, the celebration began to spread, and, on September 8, 1264, Pope Urban IV issued the papal bull "Transiturus," which established the Feast of Corpus Christi as a universal feast of the Church, to be celebrated on the Thursday following Trinity Sunday.
Digression: I have an absolute fascination with everything in Liege. The city is the hometown of my favourite saint, Christina the Astonishing, Virgin (always pronounce the comma as she wasn't just an astonishing virgin)
Back to the history lesson: At the request of Pope Urban IV, St. Thomas Aquinas composed the Divine Office (the official prayers of the Church) for the feast. This office is widely considered one of the most beautiful in the traditional Roman Breviary (the official prayer book of the Divine Office or Liturgy of the Hours), and it is the source of the famous Eucharistic hymn "Pange Lingua Gloriosi" From this classic hymn we also have another "Tantum Ergo Sacramentum." The tune popular in Australia has been given a beautiful contemporary setting by Matt Maher. In this pic of the era you can see Tom and Urban discussing a fishing trip. Waiting patiently to the side is the learned St Bonaventure who missed the boat that day.Image source
Digression 2 Dear old Google has managed to cause great confusion among traditional Catholics. When you do a Google image search for "Corpus Christi" you don't actually get the cool religious images unless you choose the "Feast" tab. . The default choice includes scenic views from the City of Corpus Christi.
The 2017 Corpus Christi Procession collection is here. See the Brisbane Corpus Christi Procession 2016 here.
To leave you with a woman's insight of what the feast of the Body and Christ is really all about I suggest you sit with the image and text of Laura Facey
I dedicate this page to the brave people and Bishops who protested at the 1981 naming of the USA attack submarine, Corpus Christi.