I felt challenged by a question , which appeared on Quora: “In layman’s terms, what is the concept of Lagrangian points?”. Thus, I proposed a first explanation. The problem is that I did not know what a celestial mechanic layman really was. Although my explanation did not require any mathematics or physics at a higher level than Senior High School, thinking it over, the level of my essay was somewhere near the upper limit of SHI knowledge. Perhaps I betrayed my (not many) english speaking readers. Therefore, I recasted the essay in the form presented here: Part I does not contain a single equation, and begins with an intuitive explanation of what the Potential of a Vector physical quantity is. Part II contains, in the form of Notes, the mathematical parts, which appeared in the first Edition. I hope that this II Edition can satisfy anybody. I cannot imagine a simpler explanation, but who knows?