Picture one heavy stroke that opens a thing along its own line. Not sawing, not tearing: the axe comes down, the log falls into two clean halves, and the faces are flat. Two details travel with that picture wherever the word goes. The break is sudden, and it follows a line the material already had. Everything in this map can be read as that stroke landing on something else.
This cleave comes from Old English cleofan, to split or separate, from Proto-Germanic kleubana and a Proto-Indo-European root meaning to cut or slice. The splitting was there from the start.
這個 cleave 來自古英語 clēofan（劈開、分開），再往前是原始日耳曼語 kleubaną，最後追到印歐語根「切、削」。也就是說，「劈開」從一開始就是它的本義，後面的用法都是把這一記重擊搬到別的東西上。
Wiktionary (kaikki) etymology 1 supplied in this evidence packet, source_ref kaikki:3f6f69a190036ae4:800574174:34696
Three branches
一記重擊，把實體劈開
這一組就是核心畫面本身，以及它被兩個專業領域接手之後的樣子。三個用法共有一件事：斷口是可以預測的，因為它順著材料原有的線。
verb · C2
Literary. To cut something into separate parts with a heavy tool such as an axe, usually in one strong stroke; also, of a material, to be able to be split in this way.
劈開；劈成兩半
劈開的是人群：使分裂
斧頭換成了一條馬路、一個議題或一場爭吵，被劈開的換成村子、議會、家族。乾淨俐落的斷口跟著一起搬過來，所以它比 divide 重得多。
verb · C2
Formal. To divide something into two completely separate parts, especially a group of people, a country or a place that used to be one whole.
使分裂；把整體劈成兩半
劈開的是看不見的一整塊
這一組把空氣、黑暗、寂靜寫成一整塊實體，然後讓某個快速的東西穿過去，留下一道縫。它是固定的文學句型，不是這個動詞自己另一個意思。
verb · C2
Literary. In the pattern cleave the air, cleave the darkness, cleave the silence: to move fast through something and open a way through it, as if cutting it.
（文學用法）劃破空氣／黑暗／寂靜