How the Waters closed above Him — Narcissus

History in the last line hints that the boy drowned is a recorded event long time ago. Narcissus, daffodil, and lily are flower names often mixed. "Lilies bold above the boy" sounds like a revenge. Narcissus is probably the most famous boy that not many feel sorry for his death.

How the Waters closed above Him
We shall never know－
How He stretched His Anguish to us
That－is covered too－

Spreads the Pond Her Base of Lilies ⁵
Bold above the Boy
Whose unclaimed Hat and Jacket
Sum the History－

(F.941/J.923)

[1] Him:: Narcissus, a handsome hunter in Greek myth.
[3] His Anguish:: his beauty unacknowledged by the world.
[5] Lilies:: persons of exceptional whiteness, fairness, or purity _{(OED 3a)}, those fair women rejected by Narcissus.
[6] Bold:: a hint on Narcissus' boldness.
[7] Jacket:: an outer garment for the upper part of the body _{(OED 1a 1462)}.
[8] History:: a recorded event long time ago.

There are several species of the Narcissus. The Yellow Narcissus is better known as the Daffodil, and bears much resemblance to the Yellow Lily. ─ The Language of Flowers (1852)

Of this rich and fragrant flower there are many varieties, that pass under different names, but all under the general name of Narcissus. The Daffodil and Jonquil are species of the Narcissus. . . . The cup, in the centre of this flower, was said to contain the tears of Narcissus, a youth, who seeing his own image reflected in a fountain of clear water, became so enamoured of himself, that he pined, and at last, in despair, killed himself. His blood was changed into this flower. . . . Other poets have, very erroneously, made the Daffodil and Lily the same flower. ─ Flores Poetici (1833)