Rule A1

So I've been trying to think of how this next rule relates to a holiday...any holiday would do, and I can't think of anything. Congratulations, Thomas B. Marlow has just decided to write a second book (or chapter, I suppose) called Thomas B. Marlow's Rules for Everyday Life! Plan on a release date approximately 6 months after the holiday book is completed - or "never," for those of you still in "reality."

Moving on... I present Rule A1*: The Proper Installation and Use of Light Switches

*Clearly, the numbering system will have to be reworked for the publication. Bear with me for now.

Light switches are vital to the health of a room - they control the flow of electricity to the room, turning a scary-at-age-5 staircase into something more bearable, something with fewer monsters. They also have the power (ha!) to render a room almost uninhabitable, if misused.
If there is one switch leading to a light, the switch should be installed so that electricity is flowing when the switch is UP. It just makes sense.
If there are two switches leading to one outlet or light, things get more complicated. When both switches are in the DOWN position, the light should be off. The light should be on if one switch is UP and one is DOWN. The switches should never be both UP - at that point the light would be off, and therefore the switches should both be DOWN. Nothing is more disconcerting than a stairway, for example, with mismatched light switches at either end.