classic waka stream

君が代は富の小川の水澄みて
千歳を経とも絶えじとぞ思ふ
Roma-ji

Kimi ga yo wa tomi no ogawa no mizu sumite chitose o fu tomo taeji to zo omou

English Translation
Our lord's reign is like
the little river of Tomi,
its waters so clear,
though a thousand years go by
it will never cease, I think
Meaning
Like the clear waters of the Tomi stream, our lord's reign, I believe, will never cease though a thousand years go by.
Commentary
Book Five Celebration Poems 327

Like the clear, ever-flowing waters of the Tomi stream, the sovereign's reign will never cease though a thousand years pass, the poem says. The Tomi stream is a poetic place in Yamato, sung as a river that never runs dry, as in the Shūishū poem said to have answered Prince Shōtoku, vowing never to forget the prince's name unless the Tomi stream at Ikaruga should cease. Letting the river's name ring with tomi, wealth, the poem celebrates the reign.
This poem and the next poem, 328, form a pair celebrating the long reign through a river of old legend and the sun goddess.

First line, 'kimi ga yo wa', is the same first line as poem 325 in this book.
Second line, 'tomi no ogawa no', is a stream at Ikaruga in Yamato, its name echoing tomi, wealth.
Third line, 'mizu sumite', means its water clear, laying over it a reign untroubled and well ordered.
Fourth line, 'chitose o fu tomo', means though a thousand years pass, the concessive supposition tomo.
Final line, 'taeji to zo omou', means it will not cease, I think, zo binding with the attributive omou. It answers 'should it cease' in the Shūishū poem.
Source
Kinyo Wakashu
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