Buddha's own simple truth was that nirvana is right here and now. It is within each of you. And it is up to you to uncover it and live it in the present moment, not through the layers and rituals that different men and women have added, but through what should be very simple teachings.
As someone who has studied Buddhism (read: slightly above Wikipedia-level knowledge), I see several important concepts that resonate in the outcome of the series.
"All the suffering in the world comes from seeking pleasure for oneself. All the happiness in the world comes from seeking pleasure for others." That, I believe, captures the essence of this.