Picture a route drawn on a map, and one mark at the front of it. That mark is not the best part of the route and it is not where anyone wants to stay; it is simply where the line begins, so that everything else has somewhere to run from. English uses that mark for real ground, where a walk or a race begins, and for thinking, where a fact or a question is set down so a discussion can move off it.
From the picture
想法或過程的起頭
同一個記號，這次畫在想法上：先放下一篇文章、一個問題、一份資料，後面的討論和計畫就從那裡往外長。這是理解上的連結，不是在主張哪一個用法比較早出現。也正因為只是「第一個點」，它不必是正確答案——英文才會有 only a starting point 這種說法。
noun · B2
An idea, fact or situation that you begin from, and that a discussion, plan, piece of work or process can then grow out of.
出發點
noun · B1
The place where a journey, a walk, a race or a route begins.
起點