What is the theme of the poem “Spring and Fall” by Gerard Manley Hopkins?

Margaret, are you grieving
Over Goldengrove unleaving?
Leaves like the things of man, you
With your fresh thoughts care for, can you?
Ah! as the heart grows older
It will come to such sights colder
By and by, nor spare a sigh
Though worlds of wanwood leafmeal lie;
And yet you wíll weep and know why.
Now no matter, child, the name:
Sorrow’s spríngs are the same.
Nor mouth had, no nor mind, expressed
What heart heard of, ghost guessed:
It is the blight man was born for,
It is Margaret you mourn for.

A.
Nature outlasts man.
B.
Everything has a meaning.
C.
All things must pass away.
D.
Children are close to nature.

I'm not going to write 150 words lol, but i will you with giving you examples of how they kept the animal population from revolting. napoleon made a list of rules, and told everyone how "important they are even though he was known to break them and then have them changed by the only animal who could read on the farm. none of the animals were intelligent enough to read, so they never knew if they had been changed or not which was an advantage to napoleon. napoleon constantly reminded them that if they revolted they would have to go back to mr. jones' way of things, which in retrospect was "worse" (wasn't really worse though, he was just saying that to intimidate since he didn't wanna lose his power). one of the main reasons they revolted in the first place was food, and of course if they revolt napoleon will not share food with them.