Pure existence is formless. So there is no way to come to know it through perception. Neither can it be described in words. Scriptures written over ages by wise men of different cultures and traditions can help us building thoughts about it, but in no way we can fully understand pure existence through written words.
So what is left is intuitive knowledge. We all intuitively know deep inside us there is something that gives us life. And if we ignore shortly the fact that by the delusion of our senses and self-awareness we consider this to be something individual, most people intuitively feel that this energy inside us that makes us live in essence is something very pure.
If we awake from dreamless sleep by intuition we know that we did not know what was going on for the past hours. That is a proof that intuitively we know there is something inside us that is always there. Even during dreamless sleep since that what is inside us is aware of void too. It only does not act. This same intuitive knowledge is the only way to understand pure existence which is the non-active source of everything.
Since pure existence is believed to be formless, non-active and permanent we cannot understand it through action. Action generates some kind of effect, effects lead to modifications. Because of its very nature pure existence is non-modifiable, so consequently any actions are fruitless to come to the understanding of pure existence.
This actually raises an issue about how we have to understand the act of thinking. Is thinking an action yes or no? Again maybe we have to differ at this point between thinking and intuitive knowledge. Thinking itself although not really being a physical action can under circumstances also lead to effects. Let’s say it can be seen as a mental act that through its conclusions can lead to physical actions and that way also lead to effects and consequently to modifications. Through reasoning we can decide to do things in order to change our lives. Like for example we can decide that it might be a good idea to go on a pilgrimage or to join a certain community. These decisions initiated by mental thinking will finally lead to actions. These actions will lead to effects and modifications. That way seen also pure reasoning cannot lead to the understanding of pure existence.
In that sense intuitive knowledge is different. Unlike reasoning about things where intuitive knowledge is concerned we just know. Unfortunately mostly on base of this intuitive knowledge we start reasoning and that way things go astray. We know there is something inside us giving life, starting to reason about it we create a subject-object oriented view leading to the concept of an individual ego. This conclusion on its turn leads to actions, effects, modifications. And here we go, in the game of delusion the ball is rolling.
If through reasoning we try to understand pure existence we will only create our individual modifiable idea of it. If we try to describe it in words we will also just create an individual modifiable view on it. The moment we write down the first word, we leave space for subjective interpretation, we make the subject of what we describe modifiable and that while it is not modifiable of nature.
So for that reason even if through intuitive knowledge we would understand and experience pure existence we would have no means to transfer this knowledge in its pure form to others in some kind of descriptions, guidelines, or whatsoever. Because of the natural limitations of human communication leaving always space to subjective interpretation, any shared knowledge on this matter can only be a support to the realization of intuitive knowledge but can never be authoritative of character.