Just like doctors, medical practitioners, they first of all ply their knife on the dead body and find out where are the nerves, what are the . . . not a living man. When they are fully practiced, then they are allowed to practice surgical operation.
Similarly, kṣatriyas are meant for sometimes killing. Just like Arjuna, he's a kṣatriya. So Kṛṣṇa is criticizing him that, "You are a kṣatriya. You have learned how to kill, and now you are hesitating? What is the nonsense?" So kṣatriyas are taught, because they have to rule over. So if required, the demons and the culprit, should immediately cut off his head, duty of the government. So all of a sudden you cannot do that. Just like in your country a young man, he has never learned how to kill, and he is drawn in the draft board, "Come on. Go and kill." What he will do? He will hesitate. This is not perfect system. If you want a kṣatriya, you must train them. You must train a class of men as brāhmaṇas. You must train a class of men as kṣatriya and a class of men as agriculturist and cow protection, and balance are workers. That is cātur-varṇyam: brāhmaṇa, kṣatriya, vaiśya, śūdra. But the kṣatriya or the president or the secretary, they are sitting very comfortably at our home, and some poor young men—"Come on. Go and fight." What is this? What they will fight? They will die there, that's all. If he does not know how to fight, that energy is lacking, what he will do there?