撐住一個身體
最基本的一層：托住身體的那隻手就是食物。
noun · C1
Food and drink that a person or an animal needs in order to stay alive.
食物；養分
核心畫面
One way to hold sustenance: a hand under something that would otherwise sink. Not a gift, not a treat — the steady supply that keeps the thing from going down. Take the hand away and it stops. A body stops without food; a club stops without members and money. Sustenance names whatever is doing the holding up.
sustenance 的畫面可以想成一隻手托在下面，不讓東西沉下去。它不是禮物，也不是享受，而是那個「不能斷的供給」…更多收起
sustenance 的畫面可以想成一隻手托在下面，不讓東西沉下去。它不是禮物，也不是享受，而是那個「不能斷的供給」。手一收，東西就停了。身體沒有食物會停，社團沒有人和錢也會停。sustenance 講的就是正在托住它的那個東西。From the word’s history
Wiktionary traces it to Old French sustenance, from sustenir, from Latin sustinere — equivalent to sustain + -ance. Sustain is literally to hold up from below, which is exactly the image both senses use.
來源把它追到古法文 sustenance，再到拉丁文 sustinere，並說它等於 sustain 加 -ance。sustain 的字面就是「從下面撐住」，這正好是兩個意思共用的畫面。
Wiktionary entry for sustenance: From Middle English sustenaunce, from Old French sustenance, from sustenir with the suffix -ance, from Latin sustinere; equivalent to sustain + -ance — as supplied in the evidence packet
Two branches
撐住一件事
同一隻手，托的東西從身體換成制度、團體或一門生意。
noun · C1
The act of keeping something going so that it does not stop or fail.
維持；延續