In plain words
17. The student must be sumati, of good mind, not durmati, of bad mind
Envy and hatred lead to man's ruin
The root cause of all unrest and all hardship is ‘envy’. In the Gītā too, “Arjuna! You must be free of envy, you must not be envious,” Śrī Kṛṣṇa taught again and again. Along with this ‘envy’ comes ‘hatred’. These two are partners in theft. These two qualities are like poisonous worms. Or like root worms. If a root worm gets into the base of a tree that is resplendent with fruit and flowers, what becomes of that tree? Even as one watches it withers day by day, its fruit and flowers drop, and it becomes lifeless. At last it dries up and falls to the ground. In the same way, once envy and hatred enter a man's heart, however clever he is and however high the learning he has studied, he falls, becomes a traitor to society, loses his whole humanity and becomes a target of criticism. He destroys his very character; at last even his friends turn into enemies; he burns up his honour and good name, and suffers many sorrows. There is no worse enemy than ‘jealousy’. Being unable to bear the sight of one stronger than oneself, or one cleverer than oneself, or one who wins a better name and fame than oneself, or one who wears better clothes and looks handsomer than oneself; not stopping there but wishing for his fall and doing harm to his honour: such vices and faults are not the virtues fitting a student or an educated man.