Testing the temperature of a river is about as ordinary an errand as there is, and that is where the poem begins. The speaker walks down to the water's edge on a "beautiful summer night" with a small practical purpose. The errand is never finished. We never learn whether the water was warm or cold, because within a few lines the river has started to talk and the speaker has stopped acting and started listening. That swerve from doing to feeling drives the whole poem and leads to its central idea: darkness, even emptiness, can be beautiful rather than frightening.
The river is personified from the start. It "told me stories with it's flowing noise", and the word "stories" suggests the sound is more than background, that it has shape and a voice meant for the speaker. The stories comfort a "beating heart", which sets the speaker's restless body against the "tranquil" surface. Line six opens with that very word and inverts the usual order, "Tranquil was the surface that spoke to my soul", so the calm arrives before anything else, like a breath let out. The water then becomes a mirror "reflecting the stars", and a second image follows: "the gaze of the sky watching over me." The speaker looks down but feels looked at from above. The river carries the sky down to human level, so the comfort comes from two directions at once.
The poem's most interesting tension is between peace and how fragile it is. "I thought for a moment" appears twice, and the repetition works like a pulse. Each time the feeling is qualified: the speaker "could rest in peace," the moment "could have just been a shadow," it "could have just blinked." These hedging verbs show someone who doesn't quite trust the calm to last. "Rest in peace" is also hard to read innocently, since it is the language of gravestones, and the lines that follow, with their "shadow" and "void of nothingness," lean the same way. Judging by the imagery, the poem may be circling a thought about death or oblivion, though it never says so directly. What it does say is that the peace was brief.
Structurally, the poem is a single unbroken block of fifteen lines with no stanza breaks and no rhyme scheme, which suits a poem about flowing water. The lines also grow. The opening ones run to about nine syllables ("It was a beautiful summer night"), while by the middle they stretch to thirteen or fourteen ("A moment so brief that it could have just been a shadow"), as if the sentences were being carried along by the current. A loose echo links "night" in the first line with "sight" in the thirteenth, so the ending quietly loops back to the beginning. Repetition does much of the work that rhyme usually does, as with "surface" in two consecutive lines and the pairing of "even" and "still" near the end.
The final three lines carry the poem's real argument. "Even with it dark it was still such a sight" is a concession: the darkness might have been expected to spoil the view, and it doesn't. Then comes the strangest line, "The color as dark as an ink is black." The comparison goes in a circle, dark as ink is black, and it reads as though language has run out of ways to describe something so total. The last line doubles the emptiness with "void of nothingness," then turns on one small word: "but beautiful even still." Here "still" works twice, meaning both "nevertheless" and "motionless," like the water itself.
The poem is unpolished in places. "Lead" stands where "led" is meant, and apostrophes are missing or misplaced in "rivers edge" and "it's." Those slips are worth correcting, but they don't hide what the poem does well. It starts with a small, practical reason to be at the river, and it ends having looked at a void without flinching. It doesn't resolve the pull between peace and emptiness. It simply decides that both are worth looking at, and that decision is what makes it worth reading.