On Shavuot in most Ashkenazi communities, before the congregation reads Exodus 19 -20, the story of the giving of the Torah, we recite an Aramaic poem called Akdamut or "Prologues".
This 90-verse poem talks about our inability to describe God's greatness:"If all the skies were parchment, all the reeds quills and all the oceans ink…" It heaps praises on God, Israel's love and loyalty to God, and the Torah that God gave. It is a glorious poem, although the Aramaic language is very difficult.
Rabbi Meir benYitzchak of Worms (11th century) was the composer. Akdamut has been a long-standing source of debate between those who will not give up on this beautiful, sacred poem and those who maintain that it is simply too obscure to be meaningful to the vast majority.
The Singers Prayer Book, for a century the official Anglo-Jewish siddur, did not include Akdamut, whereas the new Koren Sacks Siddur does.