I've seen heaven.
I saw the almighty perfection, felt the delectable taste on my tongue, visiting for a brief moment. According to the common-sense, that would have fulfilled me - that I'd be lucky and thankful while walking on clouds after such a lovely stay.
But Earth has never felt so much like hell and I have never been more lonely. That short glimpse of heaven did not fulfilled me, for it cold-heartedly carved a hole in my chest.
Once I had felt that delectable taste of undistorted joy, I could never be satisfied by anything else again.