《水经注·卷一》
《释名》说：河，就是下，循着地势低洼处而流。
《释名》曰：河，下也，随地下处而通流也。
"Shiming" states: A river is what flows lower down low lands.
<s>[INST] Kindly elucidate the central themes in this passage in English: 《释名》曰：河，下也，随地下处而通流也。 [/INST] "Shiming" states: A river is what flows lower down low lands.</s>
Kindly elucidate the central themes in this passage in English: 《释名》曰：河，下也，随地下处而通流也。
user
"Shiming" states: A river is what flows lower down low lands.
assistant