classic waka stream

その夢を問はば嘆きやまさるとて
驚かさでも過ぎにけるかな
Roma-ji

Sono yume o towaba nageki ya masaru tote odorokasade mo suginikeru kana

English Translation
That dream, should I ask
of it, would your grief not then
grow all the greater,
so, not stirring you awake,
I have let the days slip by
Meaning
Thinking that asking about that dreamlike event would only deepen your grief, I let the time pass without stirring you with a message.
Commentary
Book Ten Miscellaneous Poems II 616

Fearing that asking about that dreamlike event would only deepen the other's grief, the poet let time pass without sending word. He explains that his delay in sending condolence to someone who had lost a family member came from consideration for that person's sorrow.
The dream stands for a death and odorokasu carries the sense of waking from a dream, and with the next poem, 617, between them, 618 also sings of waking from a dream.
The author, Masafusa, is Ōe no Masafusa, a son of Ōe no Narihira, who became Provisional Middle Counselor and Acting Governor-General of Dazaifu. Known as the foremost scholar of his day, he was called Gōsotsu. One of his poems appears in the Ogura Hyakunin Isshu.

First line, 'sono yume o', means that dream, pointing to a death as fleeting as a dream.
Second line, 'towaba nageki ya', means if I asked, would grief, the irrealis with ba expressing a supposition. The particle ya of question is answered by the attributive masaru in the third line.
Third line, 'masaru tote', means thinking it would grow greater.
Fourth line, 'odorokasade mo', means without startling you, using the negative particle de. Odorokasu, to wake from sleep, is associated with yume, dream.
Final line, 'suginikeru kana', means I have let it pass, the perfective nu and exclamatory keri followed by kana.
Author
Oe no Masafusa
Source
Kinyo Wakashu
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