Picture one or two sentences, short enough to paint on a wall, that answer a single question: why does this exist, and what is it trying to do? The sentences are meant to be seen. Because they are out where people can read them, they work in two directions at once — they point the way forward, and they can be held up afterwards against what was actually done.
可以想成一兩句話，短到可以直接漆在牆上，而且只回答一個問題：這個東西為什麼存在、想做到什麼？重點是它被放在看得到的地方。因為公開，它就同時往兩個方向作用：往前，它指出方向；往後，別人可以拿它來對照你實際做了什麼。兩個用法的差別只在於，牆上那句話寫的是一個組織，還是一個人。