But presumably it isn't an ill-defined moment to a spirit—that's my point. Something changes at an instant that is sunrise or sunset, and that change at that instant dismisses spirits, fulfills or breaks Geasa, and probably does a bunch of other things that I don't remember.

Which is the other point—not only does redefining spirit existence duration as some specific amount of time not really solve the issue of sense with regard to spirits (why exactly that amount of time?), but it leaves the problem still in place elsewhere.

Edit: I'll pick this discussion back up Thursday evening or Friday--it's exam week, so I'm redirecting dumpshock.com to localhost for the duration.

~J

It does, however, solve one very important issue; that of game balance, which must in all situations take priority over all fluffwise considerations, or else accept without complaint the inevitable brokenness which shall result, such as infinate-duration spirits of air.

For the most part I have played magician characters (usually shamanic) through all four editions, and I guess I just fail to see a lack of game balance with the sunrise/sunset issue. I see it as just the way Magic works, and always has worked.