This world is not conclusion

This world is not conclusion;
A sequel stands beyond,
Invisible, as music,
But positive, as sound.
It beckons and it baffles;
Philosophies don't know,
And through a riddle, at the last,
Sagacity must go.
To guess it puzzles scholars;
To gain it, men have shown
Contempt of generations,
And crucifixion known.