Sayakesa wa omoinashi ka to tsukikage o koyoi to shiranu hito ni towabaya - Kinyo Wakashu(English Translation & Meaning)

さやけさは思ひなしかと月影を
今宵と知らぬ人に問はばや

Roma-ji: Sayakesa wa omoinashi ka to tsukikage o koyoi to shiranu hito ni towabaya
English Translation: Is this brilliance just
what my fancy makes of it?
Of the moon's clear light
I would like to ask someone
who does not know what night it is
Meaning: Is the moon's brilliance only my imagination? I would like to ask about this moonlight someone who does not know that tonight is the night of the full moon.
Commentary: Book Three Autumn Poems 185

Tonight's moon seems especially bright, but perhaps only because the poet knows it is the fifteenth night, so he would like to ask someone unaware of it. The poem has an intellectual turn, wishing to test whether the brilliance of the harvest moon is real or only his own fancy.
From poem 174 through poem 217 in this book a long sequence of moon poems follows, from the evening moon through the bright moon of the fifteenth night of the Eighth Month to the moon at dawn, singing of the moon in all its aspects and of the heart that gazes on it.

First line, 'sayakesa wa', means its clear brightness, the brilliance of the moon.
Second line, 'omoinashi ka to', uses omoinashi, fancy or imagination: wondering if it is only fancy.
Third line, 'tsukikage o', means the moonlight.
Fourth line, 'koyoi to shiranu', means not knowing that tonight is the night of the full moon.
Final line, 'hito ni towabaya', uses baya, a final particle of one's own wish: I would like to ask someone.
Source: Kinyo Wakashu
Prev Poem: Azumaji o haruka ni izuru mochizuki no koma ni koyoi ya ausaka no seki
Next Poem: Aki wa nao nokori ōkaru toshi naredo koyoi no tsuki no na koso oshikere