St. Thomas Aquinas' hymn Tantum Ergo, which is usually sung at Benediction, always seems better in Latin:
Et antiquum documentum
Novo cedat ritui:
Mainly because in both the transliterated and the literal translation it doesn't make a ton of sense:
And let the old practice
Give way to the new rite;
Given this is written over 1000 years after the rite was established, what is this line in the hymn about?