Xena: Warrior Princess, Season 1

Gabrielle:
Once, a long, long time ago, all people had four legs and two heads. And then, the Gods threw down thunderbolts, and split everyone into two. Each half then had two legs, and one head. But the separation left both sides with a desperate yearning to be reunited, because they shared the same soul. And ever since then, all people spend their lives searching for the other half of their soul.