A drunk is searching the ground under a street lamp. A friend gets there and asks him what he is doing. The drunk slurs, “I’m looking for my key.” The friend helps him search every where. Half an hour later they still have not found the key. The friend asks, “Are you sure you lost it here?” “No,” replies the drunk, “I lost it inside my house.” “Then why are you looking here?” “Because the light is here.”