Gervase of Canterbury (c.1141-c.1210) was a monk of Christ Church in Canterbury. He was ordained on February 16, 1163 by Archbishop of Canterbury Thomas Becket (who would be assassinated in 1170, canonized by Alexander III a few years later, and become the focus of the most famous shrine in England).
Gervase had a fairly undistinguished career as a monk, and his "importance" for us is in his connection to other people and events. He was involved in the dispute between the monks of Christ Church and Archbishop of Canterbury Baldwin of Forde. Baldwin disapproved of the luxury in which the monks of Christ Church lived, derived from the donations made by pilgrims to the shrine of St. Thomas Becket. At one point, Baldwin had the entire monastery confined under house arrest for a year and a half. Gervase was one of the monks sent to inform Baldwin that they were making an appeal to the pope. Ultimately, the monks were given their freedom and normalcy restored (except that Baldwin appointed Roger Norris, a pretty ineffective administrator, as their prior).
For a brief time Gervase held the position of sacristan (the person who takes care of the church and its contents), working for the Archbishop Hubert Walter.
...and that's about it for Gervase, except for one little thing that has intrigued historians and astronomers for centuries. Gervase kept records and wrote books, such as a history of the Archbishops of Canterbury and his Mappa Mundi, which lists bishoprics and ecclesiastical houses in England, Wales and Scotland. He was also the chronicler of his monastery, and on the night of June 18th, 1178,* he recorded something curious and previously unseen.
...but what the event was, and how June the 25th is actually the anniversary of the event on the 18th, I'll save for tomorrow.
*The same year this was happening in Italy, as mentioned on the June 20th post.