Lord Krishna told Dharmaja,
Though Duryodhana and Dhusshaasana were born in notable royal family, they discarded the human qualities due to jealousy and hatred and brought ruin to the family and the clan. Krishna added that jealousy is a dangerous canker that eats at the root of the tree of life, while hatred is pest that attacks the trunk of the tree. Thus, the tree of life is completely destroyed by both these pests. The Kauravas were victims of these two pests and sought their own ruin.
One may raise the question as to how to get over these dangerous pests of jealousy and hatred. This is possible when you make all the sense organs function in unison.
If senses do not follow thoughts, life will become miserable. When there is forbearance, all organs co-ordinate harmoniously and work in unison
Sathya Sai Speaks Vol XXVII page 3 and 4