classic waka stream

定めなき世をうき雲ぞあはれなる
頼みし君が煙と思へば
Roma-ji

Sadame naki yo o ukigumo zo aware naru tanomishi kimi ga keburi to omoeba

English Translation
In this uncertain
world the drifting cloud of grief
moves me most deeply,
for I think of it as smoke
from you, on whom I relied
Meaning
The drifting clouds that make this uncertain world so sorrowful move me deeply, for I think of them as the smoke of you, on whom I relied.
Commentary
Book Ten Miscellaneous Poems II 622

The drifting clouds that make this uncertain world feel so sorrowful move the poet deeply, for they seem the smoke of the one the poet relied on. Seeing in the clouds the smoke of that person's cremation, the poet expresses the world's impermanence and a deep grief.
Following the preceding poem, 621, this poem too sings of drifting clouds and the smoke of a cremation. Where the preceding poem came to know that the smoke ends by mingling with the clouds, this poem sees the clouds themselves as the smoke of the departed.

First line, 'sadame naki', means uncertain, expressing impermanence.
Second line, 'yo o ukigumo zo', means the drifting clouds that make the world sorrowful, joining yo o uki, the world as sorrowful, with ukigumo, floating clouds. Ukigumo also appears in the fourth line of the preceding poem, 621.
Third line, 'aware naru', means how deeply moving, the particle zo answered by the attributive; the poem breaks after the third line.
Fourth line, 'tanomishi kimi ga', means you on whom I relied, using the attributive shi of the past ki.
Final line, 'keburi to omoeba', means since I think it your smoke, the realis followed by ba expressing a reason. It is inverted with the lines before.
Source
Kinyo Wakashu
Prev Poem
Ima zo shiru omoi no hate wa yo no naka no ukigumo ni nomi majiru mono to wa
Next Poem
Kusaki made omoikeri tomo miyuru kana matsu sae fuji no koromo kitekeri