This Advent song from Michael Joncas is a bit of an oddity. It’s not sure what key it is in. BIAB suggested D but it certainly isn’t in G nor Em as notated. Verses one. three and five have roughly the same tune with variations. Verses two and four also have a similar tune. So it is either a choir piece or the assembly is left with the refrain and the cantor does the verses and descant line in the chorus.
The text is based on Isaiah 40:1-11. You can find the words here. OCP sell the sheet music, which means it must be popular to be in GIA collection. Interestingly the guitar versions from GIA and OCP differ in that OCP crunched it two pages and lost clarity and GIA spread it over 3 pages to add a page turn. Take your pick.
I initially confused the melody and descant lines and wondered why it went so high. It is meant to be pretty fast in a faux medieval style but I didn’t take it all the way to 168 as suggested. Some of the You Tube versions slow it right down, which gives it a very different feel.