It is good to over do it when talking. Without repetition it is hard to convey enough detail. To describe something, you must often describe it incorrectly and incompletely, but in a number of different ways. By changing your tone you imply which parts of each dicription apply, and to what degree they apply. Concentrations of about 20 neuro-chemicals control the moods of the brain.
Moods are systems that monitor the brain looking for certain patterns.
Typically they stabilize brain activity, just as glands stabilize metabolic functions. They release their neurotransmitters to make your brain run faster, more right-brained, lustful, angry, hungry etc. Emotions seem to have opposites because they reflect the levels of the neuro transmitters, which change over a continuum. Love becomes hate as the level drops, sad to happy, confident to fearful, pain to comfort, hope to defeat, envy to pride, greatness to meekness, energy to slothfulness, playful to serious etc. Combinations of the base emotions form the many shades.