classic waka stream

わたつ海の底の藻屑と見しものを
いかでか空の月となるらむ
Roma-ji

Watatsuumi no soko no mokuzu to mishi mono o ikade ka sora no tsuki to naruramu

English Translation
In the ocean's depths
I had seen it as no more
than seaweed fragments,
how is it then that it turns
into the moon in the sky
Meaning
I had seen it as mere seaweed scraps at the bottom of the sea; how could it become the moon in the sky?
Commentary
Book Eleven Variant Poems 709

What had seemed mere scraps of seaweed at the bottom of the great sea has somehow become the moon shining in the sky. Contrasting the sea floor with the moon above, the poem expresses wonder at something thought worthless becoming precious. Placed among poems on the Buddha's Law, it may be read as drawing on the Lotus Sutra's Devadatta chapter, which tells of the dragon girl of the undersea palace attaining buddhahood.
This poem is found only in a variant manuscript line of the anthology; in the variant order it is placed after 636 in Book Ten. Poem 636 also draws on the Devadatta chapter of the Lotus Sutra. Poem 710 in this book likewise sings of mikuzu, scraps drifting on the waves of the sea.

First line, 'watatsuumi no', means of the great sea.
Second line, 'soko no mokuzu to', means as seaweed scraps on the bottom, a figure for something of no worth.
Third line, 'mishi mono o', means though I had seen it so, the attributive of the past ki with the particle o expressing contrast.
Fourth line, 'ikade ka sora no', means how could it, the sky's, the particle ka of question answered by ramu in the final line. Soko, the depths, in the second line and sora, the sky, form a contrast of low and high.
Final line, 'tsuki to naruramu', means become the moon, closing with ramu inferring a cause. Poem 636 in Book Ten also likens the preaching Buddha to the moon.
Source
Kinyo Wakashu
Prev Poem
Tsumi wa shimo tsuyu mo nokorazu kienuramu nagaki yosugara kuyuru omoi ni
Next Poem
Yomo no umi no nami ni tadayou mikuzu o mo nanae no ami ni hiki na morashi so