ok, i guess i find an answer. Those lights (lunar light...) are just lights with specific caracteristics, and you have to load them consequently. They work on the mental plane mainly, and also on the astral if the condensation is strong enough. I guess there is nothing wrong to have a little accumulation of them inside the body. If you add feelings to them (hot...), then you get an element in affinity with this sphere. It will have strong effects on the astral plane, and a little less in the physical. You should avoid condensate them in the body AND keep them inside all day long (i tried this before with fire, i saw quickly it influences quiet efficiently). I was just wondering why Bardon, in PME, didn't ask to add feelings to the condensate light for an evocation on the astral plane... Well, i'd still like to hear what you all think.