I do not agree with Plato's view that thinking (as the basis of all existing ones) is above doing and you must first think something to do it. My position is therefore that every imaginable fantasy is at the service of reality and therefore thinking is not above doing it, but rather subordinate to it in this context. I define fantasy here as conceiving something that does not reflect reality like the one looking in the mirror. I see reality as the sum of all our experiences and actions in everyday life. The theorem will be illustrated by the following examples.

1. Conspiracies
Conspiracy theories (CTs) arise from the idea that behind each event there is a responsible group. Standalone events are connected in CTs as if they would fit into a coherent story or conspiracy. For example, there is a conspiracy theory about the murder of JFK, which sees the fact that a man opened his umbrella just before the shots were fired as a signal to the killer and thus linked to the murder of the president. The theory may not be true or even complete nonsense, but it is made up of elements of reality, namely the opening of the umbrella and the assassination of the president.

2. Fabulous animals
The famous scientist and artist Leonardo da Vinci advised, when you would like to create a fabulous animal that looks a little convincing (real), you should take elements of existing animals. If you would like to think of a fantasy animal that has no elements of real animals, it is not recognizable as a fantasy animal. This may also be similar to a private language that can only be defined by a public language.

3. Martians
Probably we have thought about it once: are we alone in the universe? The answer is no anyway, because there are other people in the world than just us. However, the question of whether there are extraterrestrial life is often fantasized. The infinity of the universe creates a lot of possibilities, so maybe it's not so strange that there are extraterrestrials who, like us, sometimes reflect on what they do or think. It makes me think that the familiar aliens have two eyes, a nose and a mouth... just like us!

4. Article
Finally, writing an article is an occupation in which doing (writing it) supports conceiving it. For example, for this article, I did not have the whole text in my head in advance, but only the statement that I was going to substantiate. The examples came to mind while writing them. Examples which, by the way, all referred to what we find in reality...

These examples show that CTs cannot exist as a fantasy without the elements of the reality from which they are built. Fabulous animals do not seem convincing if they are not composed of features of existing animals. Even Martians cannot be conceived without the infinite possibilities of the universe and man as a model. Writing articles, finally, is something that requires some imagination. However, even here the (be) thinking was not the basis because it mainly happened during doing, and thinking therefore also depended on doing.
In short: without doing something we can never think anything, or in other words: without reality there is no imagination!

Fantasy in reality