This is a classic for a reason. It's one of Isaac Watts' best-known hymns. It features some bass echoes on "and heaven and nature sing" (probably on the other verses too, but the echo is only printed for one verse!). It has stuff about "plains" and "prove" which worked well for a math parody about "planes" and proving things. My choir sang an arrangement by John Rutter (famous for "What Sweeter Music" and other choral anthems) at a big multi-choir event in winter 2004, which was a couple months after the Red Sox won the World Series, so I was thinking of them during "far as the curse is found!"

There is only one problem. This is not an Advent song.

This is very clearly a Christmas carol. "The Lord is come," "the Savior reigns," "he rules the world." Present tense! He does it right now! Because he has come, we're not still anticipating him! This was categorized as a Christmas hymn in previous hymnals, and it's the last song in this edition's Advent section (we're really getting down to the last few now!), which made me literally wonder if it was a typo. It's not. The editors decided to put this with the Advent hymns.

I mean, it's a great song, but...????

The rhyme scheme is quite dense, this is something I don't think I realized until I sat down to write a math parody. "Above thy deep and dreamless sleep...The hopes and fears of all the years." The other verses are just as rich. Nice.

The sentence-level grammar is also kind of tricky, it took me a long time to parse verse 2: "For Christ is born of Mary, and, gathered all above//while mortals sleep, the angels keep their watch of wondering love." "Gathered all above" refers to where the angels are. It's not Christ is a. born of Mary and then b. gathered all above. Who would be gathering Christ all above? Very confusing.

Like Away in a Manger, this also has another melody more familiar to older generations, although that one did not make it into this hymnal.

This is the nicely-harmonized Bach chorale we've come across a couple times before, with the old text it goes to--this also shows up in Bach's "St. Matthew's Passion," so it's probably the most famous text associated with it.

I'm going to guess that the second most-famous text associated with it is not the Haugen or the Prodigal Son stuff we've seen, but rather another labor union text. The first draft of that was "Because All Men Are Brothers," but that was too sexist, so now it's been updated to "Because We All Are Family." The union choir was heavy on "just repeat this melody/harmony after me," I was one of the few people there who preferred to read music (well, let's be real, I was one of the few people there, period), so it was nice being able to be like "yes, please just let me read the alto part, it's Bach! I know this one!!"

Final verse, same as the...previous song?

Following this from Thomas Ken, we have an evening song that ends with the same verse. This music is arranged by Thomas Tallis, and is (unsurprisingly) known as Tallis' Canon--a canon is a song that can be sung in a round.

Isn't that also a Madeleine L'Engle character?

He was named after this, several centuries later.

Is this version easier to sing in a round than the alternatives?

Apparently so! The labor union choir (yes, of course I was in a labor union choir a couple years ago, shouldn't come as a surprise) had this version:

Praise boss when morning work bells chime
Praise boss for bits of overtime
Praise boss, whose wars we love to fight
Praise boss, fat leech and parasite.

Classic. Meanwhile, I'm more familiar with another version, which is probably going to be one of the last hymns we get to if we ever get there, but apparently that did not work so well as a round. Granted it also wasn't good at having...a standard meter or measure system which is kind of a good starting point.

Should we dread the grave as little as our beds?

Um...I don't know about that. I guess it means "live righteously, so that you won't worry about going to hell," but I think this could lead to some unintended consequences if taken too far. Granted this was written in the 1600s so maybe people were more worried about dying of ..well the plague predates the 1600s. Colic maybe, per Wikipedia.