Pandora's Superposition
Perhaps you sit in a theater in a castle far across an impassable chasm. Perhaps you dance in a phantom ballroom covered in waves of grief, buried at the bottom of the mine shaft that is the deepest depth of the sea.
If life itself truly is such a scarce substance, and one which can induce alternately such euphoria and such dysphoria...
Then it would not be remiss to describe it as a drug. Those who become addicted lose the ultimate thrill and meaning of enjoyment. They think they are stuck in the endless now, but in reality, they are stuck in the past.
They believe simultaneously the worst and the best of those around them - those closest and dearest to them, while the truth of those souls drifts determinedly, purposefully (vitally) away.
One begins to hallucinate eternity. One begins to subsume and then again osmose a new, duller future with its own bleak origin. One with terribly sharp fangs bared at the observers.
To exist - to be able to exist! - within and without, at once...so much of life consists in one's own mind. But so much more lies beyond. Mortal humans have no say at all in that.