It's traditional in Japan to have a Shinto Priest come out and 'appease the spirits (Kami)' when starting big construction or house repairs like we are at Treeleaf. My wife and mother-in-law insisted.
I don't know so much about appeasing the spirits, but I do know about appeasing my wife and mother-in-law. So, we had it done. You can see a few minutes of the ceremony here (those Shinto priests sure have cool Heian Age clothes, and, like Japanese Buddhist priests, some smooth dance moves). Unfortunately, it all made Leon start crying (especially when the Kami-nushi, or 'Spirit Master', let out a couple of cries to wake the dead ... listen in the middle for that. Hope it made the spirits smile).
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My attitude toward such things is, well, 'Don't know if it will help, but it sure can't hurt'. Some of the rocks, trees, grounds and such around the building ... even the building itself ... sure feel sometimes that they might have a little spirit to them. Who knows?
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I don't think I believe in such spirits quite literally beyond the human mind, but I could be wrong. So, I call it "winking at the gods ... giving them the benefit of the doubt, and asking for the benefit of the doubt from them too" ...