Every human being exhibit Quantum state, one is Zero state (with Ego) another is Infinite state (Egoless state). Mystics of the world who attained this Infinite state have written volumes to convey their message and ecstasy of living or enjoying or celebrating the Infinite state. I tried to give another perspective to it.
A Mystic is living from your point of view, while at his end the journey is finished so becomes like a (living) dead body. Osho says that you will attain to your ultimate potential only when you die, it means the death of the ego. Once ego died, now there is no way to connect of get affected with this world around. He is not affected by pleasure and pain, sorrow and happiness etc is actually a sober way to describe his state so that you too try to discover the lost kingdom within.
Osho used to provoke such Sober persons to remind them that their claim of ’death’ is skin deep only. Really dead person (or enlightened person) does not respond to such provocations.