"Upward" wouldn't be known without "downward" and "heat" couldn't be known without "cold", while each are opposites they are co-dependent for either one's realization: these were creations that existed as dialectic only in human thinking and couldn't be confirmed outside of which, and especially could not be said to exist in a condition external to human thought like independent matter and a world outside of personal subjectivity or as an empirical reality when not conceived in unity and from the standpoint of the human mind.