The fact is that there must be in the society four classes of men. Because sometimes violence is required. Just like why government is maintaining the police force, the military force? It is required for keeping law and order. So violence is bad, that's all right; but sometimes it is required. Just like poison. Poison is bad, but sometimes it is required for administering medicine. Even poison is administered. When one's heart is . . . according to Āyur-vedic system, when the man's heart is almost to fail, at that time, poison is given, so the heart becomes again agitated. In the medical science also. So poison is poison, but sometimes it requires as medicine administration. Similarly violence, killing, is bad. But there is circumstances where violence is righteous, religious. Therefore Kṛṣṇa says, dharmyāddhi-yuddha.
So it is the kṣatriya. Kṣatriya means who gives protection the citizens from being hurt by the irreligious person. That is called kṣatriya. Kṣat. Kṣat means injury, and tra means deliverance. Just like Mahārāja Parīkṣit. When he saw that a black man, Kali, was going to kill a cow, so he was going to inflict injury to the cow, and immediately Mahārāja Parīkṣit took his sword, that to give protection to the cow from the injury of the black man. So that is violence required. Tit for tat. One who is going to commit violence unnecessarily, the king, government, should immediately take the sword and kill that person. That is government's duty. Had it been Vedic culture prevailing now, all these persons who are unnecessarily killing the cows in the slaughterhouse, they would have been killed by the king: "You have done so sinful." So that kind of killing is pious. To give protection innocent citizen or animal from being injured by the rascals, the government or the king should take his sword and kill immediately. This kind of killing is there in the Bhagavad-gītā.