Fullmetal Alchemist Season 1 Episode 28

It was the only clue Izumi offered, as she dumped young Ed and Al on the island of Yock: "One is All, All is One." It was perhaps the most ancient tenant of alchemy, but what did it mean? And how would it help these children survive in this savage place-with no food, no shelter, and a beast lurking in the woods? Years later, the lesson must be relearned.