Because he wanted sweet dreams.
or
Wet.
or
Seven. One to install the new bulb and six to figure out what to do with the old one for the next 10,000 years.
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Only one, but the bulb has got to really WANT to change.
or
They take short cuts!
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A whole synod. One to move that the bulb be changed while the others debate until the room spins.
or