To feel one of the polarities is to negate the other. In other words, if you are expressing anger, you are not expressing tenderness at the same time. This is more than just an idle thought. It is quite instructive for therapists and leads to important questions. A simple grasp of the above six feelings can be deceiving.
Sadness provides a good example.
A person can be sad in the here and now due to a loss. That is real sadness. But an adult can still be sad in feature and expression due to the loss of a mother when he was three. That is an old feeling we sometimes call a Reflexion because it occurs as a reflex built into the musculature. In addition, there can be sadness that was copied from a father, a mother, or someone else.