Two: One to screw it in and one to observe how the light bulb itself symbolizes a single incandescent beacon of subjective reality in a netherworld of endless absurdity reaching out toward a maudlin cosmos of nothingness.
There were two cows in a field. The first cow said "moo" and the second cow said "baaaa." The first cow asked the second cow, "why did you say baaaa?" The second cow said, "I'm learning a foreign language."