Minasoko no tama sae saya ni mitsubeku mo teru tsukuyo kamo yo no fukeyukeba

水底の玉さへさやに見つべくも
照る月夜かも夜の更けゆけば

Roma-ji: Minasoko no tama sae saya ni mitsubeku mo teru tsukuyo kamo yo no fukeyukeba
English Translation: Even the jewels
deep beneath the water's face
could be clearly seen,
so bright the moon is shining
as the night grows ever late
Meaning: So brightly does the moon shine that even the jewels at the bottom of the water could surely be seen clearly—for the night is growing late.
Commentary: Book Seven Miscellaneous Poems 1082

Headnote continued from the preceding poem: "On the Moon"
As the night deepens, the moonlight grows so clear that even jewels on the bottom of the water seem visible; the poem praises the brightness of the moonlit night. The transparency of the water and the purity of the moonlight overlap in a beauty of perfect clarity.
In the moon group, poems 1071 and 1075 lament the growing lateness of the night, but here the deepening night is seen as heightening the moon's brilliance. The poet is unknown.

The first line, "Even the jewels deep beneath," refers to the bottom of the water.
In the second line, the particle "sae" (even) means "even the jewels on the bottom," and "saya ni" means clearly.
The third line, "could be clearly seen," combines the perfective "tsu" and the conjectural "beshi," strengthening the sense of certainty.
The fourth line, "so bright the moon is shining," ends the statement with the exclamatory "kamo," and the poem pauses here in wonder at the bright moonlit night.
The final line, "as the night grows ever late," adds the reason afterward by inversion: because the night is deepening.
Source: Manyoshu
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