There is Hope to win with negative power which is cruel, unexpected and undefined. Dashain is one part of believing positive attitude and winning with negative part. There is fight with both right and wrong always win right because there is rule to run this world if rule break there is end of world. Dashain start from our Holy Devy Durga Bhawani Battle with Devil Mahishashur till 10 day and kill him to rule this world with positive attitude.
So Dashain is the Festival of forget negative attitude with new positive attitude or Win with negative with Positive attitude.