This brahma-bandhu, he knew how to create this brahmāstra. He learnt it. But he knew it also that this weapon is not to be used generally. In very, very rare cases this should be used. As I explained, that atomic bomb, the nuclear weapon, is not used when there is fight between two dogs. It is not so insignificant. When the fight is very severe . . . Just like your country used this nuclear bomb. When the Japanese people dared to attack your Pearl Harbor, at that time, your president was Mr. Truman. So it was not to be used, but he took little more precaution. Anyway, such weapon, deadly weapon, should not be used ordinarily. Therefore here it is said that prāṇa-kṛcchra upasthite. He knew that Arjuna was after him and there is no escape. He would be killed. So whatever last resort he knew, he used that knowledge to throw brahmāstra so that the other party may be killed altogether. But ajānann api saṁhāram. He was not willing, but he did not know how to withdraw that. Formerly, they used to know it. They could throw one brahmāstra, and if he likes he can withdraw, or the other party, he can nullify it. This is warfare. But he did not know that. How to counteract it, he did not know that.
Another point is here. Athopaspṛśya salilam: this mantra weapon is so strong that it can be manufactured simply by touching water with mantra. Just like we take mantra, Sanskrit, apavitraḥ pavitro vā sarvāvasthāṁ gato 'pi vā yaḥ smaret puṇḍarīkākṣaṁ sa bāhya (Garuḍa Purāṇa). The same process. Do not think that it is some ritualistic external. No. It has got meaning. If you can chant the mantra properly, if you follow the rules and . . . You must be expert in chanting mantra. Hare Kṛṣṇa mantra we are chanting, and Haridāsa Ṭhākura is also chanting. So Haridāsa Ṭhākura, how advanced he was, just imagine. He was a young man, and a very nice, beautiful prostitute came there at dead of night, wanted to enjoy his company, and he said simply, "Very good idea. Please sit down. Let me finish my Hare Kṛṣṇa mantra." Is it possible for ordinary man? No. It is not possible.