Hitogokoro nani o tanomite Minasegawa seki no furukui kuchihatenuran - Senzai Wakashu(English Translation & Meaning)

人心何を頼みて水無瀬川
堰の古杭朽ち果てぬらん

Roma-ji: Hitogokoro nani o tanomite Minasegawa seki no furukui kuchihatenuran
English Translation: Trusting in what part
of another's fickle heart
has it, at Minase,
the old stake of the river weir,
rotted quite away like this?
Meaning: Trusting in what part of a fickle human heart have I, like the old stake of the weir on the Minase River, rotted away to nothing?
Commentary: Book Fifteen Love Poems V 915

Headnote: "Composed on the theme of love at the poetry contest at the house of Middle Counselor Kuninobu"
Composed on the theme of love at a poetry contest held at the residence of Middle Counselor Minamoto no Kuninobu. Trusting in what part of a human heart, he asks, has the old stake of the weir on the Minase River rotted away? In the old stake that rots as it goes on standing against the current, he sees himself, who has waited on, trusting in a lover's unreliable heart, only to waste away in vain. The name of the Minase River, said to flow underground with no water showing, echoes the emptiness of having nothing to rely on. The fourth line in the text reads "seki no furukui," which does not match "sese no furukui" in the line of kana readings; the text is followed here.
The author, "Fujiwara no Mototoshi," was the son of Minister of the Right Fujiwara no Toshiie. Though he did not rise high in rank, he was a pillar of the poetic world, ranked alongside Minamoto no Toshiyori, and was the teacher of Fujiwara no Shunzei, the compiler of this anthology.
Poem 951 of this book, "kono yo ni hito o tanomikeru kana," likewise regrets having relied on another. The word "kuchihatsu" is also shared with poem 940, "osauru sode mo kuchihatete."

First line, "hitogokoro": the human heart, here the lover's heart, often sung of as something that changes.
Second line, "nani o tanomite": "trusting in what," a lament at having relied on a heart with nothing reliable in it.
Third line, "Minasegawa": a river in Settsu and a famed place in poetry. It was said to flow underground with no water showing, echoing the emptiness of having nothing to rely on.
Fourth line, "seki no furukui": "seki" is a weir that dams a river's flow, and "furukui" an old stake driven into it. In the stake that goes on standing against the current, he sees himself waiting.
Fifth line, "kuchihatenuran": "nu" is the perfective and "ran" the present conjectural "ramu" guessing at a cause, "why has it rotted away?" It answers "nani o" in the second line. It is the same word as "kuchihatete" in the third line of 940 of this book.
Author: Fujiwara no Mototoshi
Source: Senzai Wakashu
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