Buddha in his sermon, also known as ‘Prajnaparimita hridayam Sutra’, to his enlightened disciple Sariputra said in second para “Here, O Sariputra, form is emptiness and the very emptiness is form; emptiness does not differ from form, form does not differ from emptiness, whatever is emptiness is form, whatever is form, that is emptiness; the same is true of feelings, perceptions, impulses, and consciousness.”
A witness or Sakshi or Drishta is one who is able to see both together ie Form in emptiness and emptiness in form.
Osho in his talks on The Heart Sutra further explained that as farther as science will progress it will only move towards spirituality because it is also a kind of science. Here the air around us that we feel as emptiness is behaving as a surface of very high viscosity liquid i.e. form! Science has proved it as true!
So at some other level of altitude its very nature is understood because of speed of supersonic the jet plane. Its nature is same above ground too or even more viscous than at that altitude but because we are moving at very slow speed it is very easy to pass through it without much resistance or we may have become accustomed to such resisting force, so that it doesn’t seems to us as a force at all.
So the reason behind its very visibility is change in plane and speed. This is what is achieved by practicing Mindfulness i.e. ‘Prjnaparimita’ or wisdom of the beyond.
Osho described it somewhere in his talks as the example of cross of Jesus. Normal people go on moving in their life in one plane or lower plane and at slow speed. This can be assumed as horizontal bar of the cross. Here one can move backward and forward i.e. past and future and this movement is so fast when one is at center there is an opportunity to go on higher altitude is continuously missed every time! i.e. happy moments or aha moments, that it is very hard to stay here so the practice of mindfulness makes one to stay in that moment. Even when we are able to stay may be for hours but what is needed is intensity of it that is defined by Ego. If one is there to feel it, then the ego is present in its faintest amount but by practice even if few moments can be achieved to stay in egolessness i.e. no-mind state, then what happens is called Satori in Zen. Now one has entered into the center of the cross from where vertical movement is possible now. Once this stage is achieved it is never lost and no one can steal it from you. This is real wealth and it keeps growing on its own, the more you share the more you get.
From this stage one can leap into last stage and this is the journey of a mystic and a thirst to achieve what the Jesus said as entering into the “The Kingdom of the God” as there will not be any time. One can remain in vertical bar and move higher and higher there is no limit to it. For daily routine one can ‘use’ the Horizontal bar i.e. world of mind but still remain on vertical bar at higher altitude too.
From there at that speed Buddha is saying to Sariputra “the emptiness if form”. Jesus was at that altitude and only one who can reach that altitude can see Jesus too still now. That is what happened to one of the disciples on third day! Because there is no time, as they entered into timelessness in infinite space, so still they all are there available for all of us and helping us.