真的跑在前面的人
核心畫面本身，一個字面上的用法。
noun · C1
Someone who runs at the front or ahead of others. In racing it also means a person who is not competing but goes down the course first, to test it and show the way.
前導者；試跑員
核心畫面
Picture a runner out in front of a group, far enough ahead to be seen alone. Whoever sees that runner knows two things at once: this one arrived first, and the rest are coming. Every use of forerunner keeps one half of that picture — sometimes the arriving first, sometimes the news of what follows.
可以想成「一個跑在隊伍最前面的人」。他跑在前頭，遠到可以單獨被看見。看到他的人同時知道兩件事：他先到了，而且後面還有…更多收起
可以想成「一個跑在隊伍最前面的人」。他跑在前頭，遠到可以單獨被看見。看到他的人同時知道兩件事：他先到了，而且後面還有一群人正在來的路上。forerunner 的每一個用法，都保留了這幅畫面的其中一半——有時候留下「先到的那一個」，有時候留下「他帶來的後續消息」。From the word’s history
Recorded as Middle English forrenner, a calque of Latin praecursor "one who runs before", and equivalent to fore- + runner.
字源記為中古英語 forrenner，是照拉丁文 praecursor（跑在前面的人）一字一字翻過來的，等於 fore-（在前面）加上 runner（跑的人）。所以這個「先跑的人」不是後來的比喻，而是這個字最初就有的意思。
Wiktionary entry supplied in packet (source_ref kaikki:3f6f69a190036ae4:820259693:17545)
Three branches
先出現的那一個
把畫面裡的「先到」抽出來，放到時間軸上：先來的那一個，後面的從它接下去。
noun · B2
A person or thing that came earlier than another one of the same kind, and that the later one grew out of, copied, or was built on.
先驅；前身
先到的那個訊號
把畫面裡的另一半抽出來：看到先跑的人，就知道後面有什麼要來。
noun · C1
A sign that appears before something else and shows that it is going to happen.
前兆；徵兆