Ashtavakra Gita 18.70 -

In our life we come across existence and its opposite, namely non-existence. About things which exist, we have no doubt or problem. About those that do not exist also, we have no concern.

But there is a third category called illusion or superimposition. It is that we encounter first, but on investigation, it ceases to be. You can call it ‘vanishing existence’. It is like darkness, obstructing our eyes. But examined with light, it vanishes. Will you say darkness is or is not? You can say neither. Such a phenomenon is called illusion. It makes itself felt initially. But on examination, it vanishes. Seeing a snake on a rope and ghost on a post, in dim light, are typical instances of this kind. Our dream is another instance of illusion.

Our wakeful world is such an illusion. It disappears in sleep, whereas we, the sleeper remain. Moreover, what we see as world is no external entity. It is only imprints in Consciousness. Like thoughts, emotions, etc. these imprints vanish every time. Can we consider anything existing based upon its vanishing imprint?

You can dent the earth, but not water, much less air and space. Can we then dent Consciousness? Whatever transpires as imprint within us – thought, emotion, feeling, memory and knowledge – is all vanishing existence. None warrants any concern whatsoever. Thus, the Knower of truth is established always in his unshakeable quietitude.