The Sea said Come to the Brook — Trout

Answer of this riddle poem is hinted by brook, a brook-trout. A trout born in a brook must go to the sea once, and return to its native brook to breed. Brook trout alludes a youngster and the sea the society. One must go see the world, and shall return to one's origin to create new lives.

The Sea said "Come" to the Brook－¹
The Brook said "Let me grow"－
The Sea said "Then you will be a Sea－
I want a Brook－Come now"!

The Sea said "Go" to the Sea－⁵
The Sea said "I am he
You cherished"－"Learned Waters－
Wisdom is stale－to Me"

(F.1275/J.1210)

[1] The Sea said "Come":: a trout's nature of going to sea (the society).
[1] The Brook:: the trout in a brook, not yet to sea.
[3] be a Sea:: become a sea-trout.
[4] I want a Brook:: a trout must go to the sea once in his life.
[5] The Sea said "Go":: the sea-trout's nature of returning to its brook.
[6] The Sea, I am he:: the sea (the society).
[7] Learned Waters:: the vast knowledge acquired by learning.
[8] Wisdom is stale to me:: wisdom becomes stale when away from one's origin.

These are pond-trout, river or brook-trout, and sea-trout. The two former being such fish as live exclusively in fresh water, and the latter, such as live, a great part of the year, in that which is salt or brackish, ascending the streams as spring advances, and returning to their native element so soon as the spawning season is over. ─ Natural History of the Fishes of Massachusetts (1833)

The brook trout is a migratory fish; when in its power, it invariably descends to the sea, and returns to perpetuate its species, by depositing its spawn in the clearest, coolest, and most limpid waters it can find. ─ Reports on the Sea and River Fisheries of New Brunswick (1852)