There is another irony here:
Conventionally, we tend to think that the Truth with capital T is a mystery, and always will be. Possibly, at best, something revealed after death, if we are lucky and the universe is set up that way. We can always know quite a bit about this physical world, the world of form, so that is not really a mystery, but the Ultimate Truth will quite probably always remain a mystery.
But when Ground awakens to itself, this too, as so much else, is reversed.
Now, we see that the Ultimate Truth is revealed to itself, so simply and plainly that it is difficult to express in words. All is God, awake void and form. There is no separate self anywhere, no I with an Other. The nature of all is God, is awake void and form. The ultimate truth is no longer a mystery.
And we also see, equally plainly, that the content of world of form is always a mystery. Whatever maps we put on top of the world of form is always only a map. There is an infinite number of ways to filter the world of form, and even if it was filtered only one way, there is an infinite number of maps possible to account for the world of form as it appears.
The nature of everything is clearly revealed, but the content of everything ultimately remains a mystery, independent of how refined and sophisticated our maps are.
What is a mystery, and what is not?
Before and after Big Mind awakens to itself, it is a mystery how something can be at all. How is it that there is this whole beyond and including existence and nonexistence, seeing and seen, mind and matter, life and death, and everything else? Of course, when Big Mind is awake to itself, this question is seen as coming from just a thought, so it falls away as an existential one, although can certainly remain in a relative sense – as something created by filtering what is through a certain story.
Before Big Mind awakens to itself, the mechanisms of samsara are ultimately a mystery, even if they are known and familiar to a certain extent. After, they are not, at least not in a general way although there is always more to learn and see about them.
In general, any content of awareness, the world of form, is not a mystery in that it is awareness itself, yet it is always a mystery in a relative sense in that there is always more to learn about its form aspect.