This is a quote by a famous person - Friedrich Nietzsche - a german philosopher.
Every word is a thought. So essentially when we speak we are communicating thoughts and ideas around. This is fundamental to any language – written or verbal. This is fundamental to how human beings communicate.
Now follow me closely.
So what is a rock?
You are probably imagining a lump of stone in your head right now. It is a rock. Someone told you its a rock; you might have learned it somewhere; saw it on tv, etc etc; irrespective of how you have come to learn – you know it is a rock you are thinking about.
All words have an origin; essentially every word is a thought. So when people first observed a rock – surely they didn't have a name for it. In fact at that stage it is similar to saying that it looks alien. Then what is it?
Well, the human beings that lived at the time never really cared to dissect a rock. Their survival goals never really demanded that they find the exact name of the object. However, they assigned a name, associated it with the pattern such objects portray, spread that idea to many generations, and thus that is how we have finally come to know that such an object is a rock.
But the fact is that pattern is never really supposed to be called a rock...and we can never really know what to absolutely call it.