I do not know what dust is, I do not know where it comes from, I only know that it settles on things. I cannot see it in the air, or watch it fall. Sometimes Im home all day but I never see it sliding about looking for a place to rest when my back is turned. Does it wait til I go out? Or, does it happen in the night when I sleep? Dust is not fussy about the places it chooses, though it seems to prefer still objects. Sometimes, out of kindness, I let it lie for weeks. On some places it will lie forever. However, dust holds no grudges and once removed it will always return, in a friendly way.