Meditation occurs when certain areas of the brain have been temporarily inhibited.  When activated, these early evolutionary circuits propel the individual to complulsively process social experience. These areas are the hypocampus, the hypothalamus, the Amygdala and the Reticular Activating System.  The hypocampus involves social memory, the hypothalamus activates drive (food, sex and other forms of drive), the amygdala activates fear, aggression and anxiety and finally, the RAS involves attention.  When these inner circuits are contacted they prompt the mind into action and prevent the deeper areas of the mind, involved in meditation to emerge.  Conversely, when there is temporary inhibition, there is interal space and quiet.