A person is stuck in a cold dark room without any light. In the room, there is a gas lantern, a gas heater, and a gas stove. The person has a match-box with only one match in it. What will he light first?
He will first have to light the match stick to light others.
He will light the match, and then the gas lantern, then the gas heater, and the gas stove. So depending on which things you exclude, you'll always know which one was lighted "first".