No thought is truly ever original. We are a product of everything we've ever read or heard or seen. The only thing that is original is our synthesis of ideas. How we are able to couple two or three or even more ideas into a hypothesis. Your mind cannot comprehend beyond what you know, only fuse together concepts of preexisting knowledge. Ideas may be similar, or they may be completely random and one wonders how someone could think something like that. The point is that whatever we say is just a synthesis of things that we have heard. We simply process or organize the information differently than other people may. The thoughts are not original in origin, but original in synthesis.