Everything
If you have experienced it, you know. A switch is forever flipped. In history it has been described as "going mad." Some consider it enlightenment, some see God, some are saved, some are lost. You aim your eyes to the sky, and step backwards--the grids and patterns of the universe suddenly tangibly visible in everything you see. It becomes apparent that consciousness was an obvious left turn in evolution--a gift, maybe, but also a sick joke--the illusion that we are unique, that we are more than temporary sex machines. The idea of self is absurdly self centered. We are all copies of copies of copies of some original spark. We put on clothes, cry, have goals and aspirations. None of it is real. It is entertainment--food for our egos. It is a frightening concept, but once you understand that you are nothing but a bundle of chance experiences and interactions with other matter, the freedom equates to the most pure bliss. Nothing matters in any feasible way, shape, or form. Walk a few steps down the road, and it becomes clear that life is beautiful. Walk further, and it becomes clear that it does not exist.