Sarbar, eugene is right about the cold and hot. Cold really doesn't exist. It is just an idea to help us understand heat. It isn't a "thing", but a lack of a "thing". Dark is a similar concept. Dark doesn't exist, but is a way to describe a lack of light. When you think you feel cold creeping up on you, you are actually feeling the heat leaving the area. But, this doesn't have much to do with the discussion.
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