One way to hold muster: bodies that were spread out are called in to one place, lined up, and looked over so somebody can count them. That is the whole picture — the calling in, and the counting at the end of it. Put soldiers in the line and you get the army meanings; put sheep in it and you get the Australian farm meanings; put a person in it and walk an inspector past, and you get pass muster. Take the line away and keep only the effort of collecting something scattered, and you get the commonest use today: mustering courage that was not all in one place to begin with.
The packet's Wiktionary entry traces muster through Middle English musteren and Anglo-Norman mostrer back to Latin mōnstrō, to show. The oldest idea is display, and it explains why calling people in and counting them share one word: you brought them together in order to show them.
來源的 Wiktionary 詞條把 muster 追到中古英語 musteren、盎格魯諾曼語 mostrer，再往上是拉丁文 mōnstrō「展示」（與法文 montrer 同源）。最早的意思是「亮出來給人看」，這正好解釋了為什麼「叫攏」和「清點」會共用一個字：把人集中起來，本來就是為了讓人看過一遍。
Wiktionary entry for muster (etymology 1), supplied in this packet as kaikki:3f6f69a190036ae4:654114467 / :654140527
Five branches
把人叫到一起、點名
這一組就是核心畫面本身，動詞和名詞各佔一邊：一個講那個動作，一個講那個場合。
verb · C1
When soldiers muster, they come together in one place as a group, usually so that they can be counted, checked or given orders. When a leader musters soldiers, they call them together in this way.
集合；召集（軍隊）
勉強湊出需要的東西
隊伍不見了，留下的是「把散落的東西集中到一點」這個力氣。被叫攏的不再是人，而是你身上不夠用的東西。
verb · B2
To gather up enough of something you need when it is hard to find — courage, energy, confidence, support, or even a smile. You either look inside yourself for it or work on other people to get it.
鼓起；湊出（勇氣、支持等）
站在隊伍裡被看過關
這次輪到你站在那條線上。長官走過來看一眼就放行，所以片語裡永遠藏著兩件事：有人在檢查，而且有個標準。
noun · B2
To be judged good enough when somebody checks you or your work. It is often used about clothes, a piece of work or a performance that only just reaches the standard.
及格；過得了關
把牲口趕攏
同一個畫面換上動物：牛羊散在幾百公頃的牧場上，被騎馬的人、狗，甚至直升機趕到同一個地方，一樣是為了清點、打記號、剪毛。來源把這一組標記為澳洲、紐西蘭英文。
verb · C1
In Australian and New Zealand English, to bring farm animals together from across a large area into one place, so that they can be counted, marked, or have their wool cut.
趕攏（牛羊等牲口）
聚在一起的一群鳥
最後一步只留下結果：一群東西聚在一起、被看見、可以被數。孔雀正好又醒目又愛成群，所以英文把這個群字給了牠們。
noun · C1
A group of peafowl — peacocks and peahens — seen or kept together. The source says it is sometimes used for storks and a few other birds as well.
（孔雀等的）一群