One must act as a brāhmaṇa. So he is accepted as brahmātmaja. Of course, everyone can claim that his father is like that. But that does not mean he has acquired the father's qualifications. That is not meaning. An unworthy son may claim that "Such and such big man is my father." Of course, from social point of view, we sometimes give respect, as it will be seen. Aśvatthāmā, because he happened to be a great personality, Droṇācārya, so he was excused from capital punishment. Otherwise, Arjuna decided to kill him. But because he was a very great man's son, guru-putra, considering that "If he dies, then guru's wife will be very much unhappy," Draupadī advised . . . She was unhappy on account of death of her sons. So they considered that Aśvatthāmā's mother, she's innocent, but on account of the son's death, she would be unhappy. So considering all these points, he was excused from the capital punishment.
So yadā aśaraṇam ātmānam aikṣata. He was running on, on the back of a horse, but when he saw that Arjuna is coming nearer, so he has no other alternative, protection. Then he thought of the brahmāstra. Brahmāstra is the last weapon. Just like it is similar to modern nuclear weapon, brahmāstra. As by releasing nuclear weapon there is radiation, similarly, we have got description that when Aśvatthāmā released his brahmāstra, there was a big radiation, people were feeling very terrible heat. And then Kṛṣṇa informed that "This heat is due to the Aśvatthāmā's release of brahmāstra," and Arjuna was advised, "Counteract it." Now they do not know how to counteract this nuclear weapon. Formerly they knew. I throw one kind of weapon, and if you are expert, you can counteract it. Now they have discovered the nuclear weapon, but they have not yet discovered the counteraction. Fight means I show some expert fighting craft or experiencing; the opposite party must also show something better than that. That was fighting. And in this way, when one party fails, he's killed. And if he's killed, then war stops—no more war. This was the system.