What does it mean to "declare his generation"? Mosiah 15:10

What does it mean to "declare his generation"? Mosiah 15:10

Abinadi is teaching the wicked priests of King Noah by quoting Isaiah.

There's some interesting doctrine in this verse, but only after this really weird phrase in English:

"Who shall declare his generation?"

Huh?

What does "declare" mean here?

Who is going to be doing the declaring?

Whose generation are we talking about?

Fortunately, Bruce R. McConkie comes to the rescue in a talk that is literally all about this topic. It wasn't really a talk, but a BYU devotional from 1975 called, "Who shall declare his generation?"

Side tangent: Every Tuesday at 10 (if I remember right?) there is a devotional at BYU held in the Marriott Center - a big hall capable of holding almost all of the student body. The topics range from spiritual to secular, with non-latter day saints invited to speak on various topics. The entire campus shuts down; you can't buy any food anywhere except a vending machine, there are no classes at that time, etc.

When I was a freshman I had a goal of going to every BYU devotional. I remember going to one that was about the string theory of quantum physics and not understanding a single word. Maybe partially because of that negative experience, the next year I stopped going. I think it was also because I was lazy. I know it doesn't sound or look lazy, but it really was laziness even though I was simultaneously taking the maximum number of courses (18 credits every semester for four years), staying up every night until 1-4 am (!!!) doing various things like working as an RA, homework, but honestly, mostly hanging out with friends/boyfriends - and in later years I was teaching 2-3 classrooms full of kids ages 11-13. I confess I kind of mocked these devotionals in my head a bit, which was pretty arrogant and stupid of me. I guess I felt irritated that they messed with my schedule, like when wanting to go somewhere (like the art museum or FHL on campus, or something like that) and then discovering it was inconveniently closed.

Answer:
McConkie says:

This means, “Who will give his genesis? Who will reveal his genealogy? Who will give the source from whence he sprang? Who will announce the divinity of the mortal Messiah?”

Oh! Excellent questions, but not for this post :-)