A university student once asked the Rebbe what his job was. The Rebbe gestured to the ceiling of his office and replied:
Do you see the light bulb? It's connected by cables to the power plant that provides electricity to all of Brooklyn. And that plant is connected to the turbine generators at Niagara Falls that provide electricity to New York State and other areas.
Each of us is a light bulb connected to an infinite energy generator. But the room may still be dark because the connection hasn't been made yet, and it's difficult to find the switch in the dark.
A Rebbe's job is to take your hand in the dark and help you find the switch.