So therefore association is so important. Saṅgāt sañjāyate kāmaḥ (BG 2.62). According to association we infect different qualities. That they do not know. But nature's law is so particular, as soon as you infect by association a particular type of quality, you have to suffer for that. Therefore Caitanya Mahāprabhu, He was asked by one devotee, gṛhastha devotee, householder, "Sir, what is the duty of a gṛhastha devotee, Vaiṣṇava?" Devotee means Vaiṣṇava. So He immediately informed him, asat-saṅga-tyāga ei vaiṣṇava-ācāra (CC Madhya 22.87): "A Vaiṣṇava's behavior should be that he should give up the company of asat, nondevotee." That is his first business. He should give up the company of nondevotee. This is first business. Because he will be infected. Therefore we insist our students that, "Don't go out." Even you are discomfortable, you should tolerate, but you should not go out of the Society. Then you will surely fall down. Surely fall down.
So if there is inconvenience, little . . . that is advised in Bhagavad-gītā: mātrā-sparśās tu kaunteya śītoṣṇa-sukha-duḥkha-dāḥ (BG 2.14). These, just like extreme cold or extreme heat, they are troublesome to the body, mātrā-sparśāḥ. On account of this material body we feel extreme cold, extreme heat. But Kṛṣṇa says: "They come and go." It is not that winter season will remain forever or the summer season also remain. They will come and go. If it is intolerable, please tolerate. Please tolerate. Then it will be all right. I have repeatedly said, Narottama dāsa Ṭhākura, tāṅdera caraṇa-sevi-bhakta-sane vāsa (Nāma-saṅkīrtana 7). Why we have opened this Society? I could have initiated, and let him remain at his home. No. The Society required. So by association we become good or bad. If you associate with goodness, then you acquire goodness quality, and if you associate with bad, passionate, ignorant, then you get that quality. So according to that quality.
This Yadu-vaṁśa, they were Kṛṣṇa's descendants. Just like when a king comes, he comes with his associates. So when Kṛṣṇa appeared, He had to marry so many wives because it was a stage to show Kṛṣṇa's supreme authority, supremacy. So the demigods came down also from different planets to help Kṛṣṇa. So these demigods became Kṛṣṇa's family. Some of the woman denizens, they became Kṛṣṇa's wife, and some of them became their sons. In this way, a huge family of Kṛṣṇa, Yadu dynasty. One crore, very big family, 16,108 wives. Each wife had sons, ten sons, and each son had ten sons. In this way children, grandchildren, and the whole family, big dynasty, Yadu family. It is estimated 100,000 hundred times. So many. Now, Kṛṣṇa wanted to leave this planet. So what will happen there? If they remain . . . although Kṛṣṇa knew that they have come from different planets, but they knew that, "We are sons and grandsons and grandchildren of Kṛṣṇa." They were very much puffed up.
So what is the difference between a demon and devotee? A demon is puffed up. That's all. Falsely. That is demon. And a devotee is submissive, meek and mild. This is the difference. The demons will . . . we go, "My dear sir, we have got these books to understand Kṛṣṇa, the Supreme Lord. So you kindly read this book. You will be benefited." "Ah, what is God? Who is God? I am God. Go away." This is demonism. And demigod or a devotee means, "Oh, here is a book, something about God, Kṛṣṇa. All right, let me read it." That is the difference. Āsuraṁ bhāvam āśritāḥ. Āsuraṁ bhāvam āśritāḥ (BG 7.15) means they don't care for God. That is the disease. Although they are under the stringent laws of God, still, they don't care for God.
So this Yadu dynasty, Kṛṣṇa thought that, "In My absence they are powerful. Because they, to assist Me . . ." "To assist Me" means . . . He had two missions: paritrāṇāya sādhūnāṁ vināśāya ca duṣkṛtām (BG 4.8). They have killed so many demons. Everywhere they came out victorious because Kṛṣṇa was there. Now, in the absence of Kṛṣṇa, they would be puffed up; therefore they would be turned again into demons, "Oh, I am belong to Kṛṣṇa's family." Just like in our country, Nityānanda-vaṁśa: "I belong to the Nityānanda Prabhu," exploiting people. The Muhammadans also, "I belong to the family of Muhammad, Hazrat Muhammad." Christ has no family; he did not marry; otherwise, some would have been very much puffed up, "I am family of Christ." So this material nature is such thing that as soon as you get little power, you become puffed up. That is demonic nature. That is demonic nature. So Kṛṣṇa wanted to take them with Him, because they came to help Kṛṣṇa, and after His departure, these demigods would turn into demons. That He did not like to see.
Therefore this Yadu dynasty was erased amongst themselves. Because there was no other person to kill the Yadu . . . and any one of the Yadu dynasty; therefore this fratricidal war was manufactured and they died. Yayāharad bhuvo bhāraṁ tāṁ tanuṁ vijahāv ajaḥ, kaṇṭakaṁ kaṇṭakena (SB 1.15.34). Kaṇṭakaṁ kaṇṭakena. Just like if you have got some thorn pricked in your leg, you take another thorn and get it out. This is the law of nature. One demon is killed by another demon. That is the keeping balance. There is war. We have experience. One demonic nation has grown up very strong, so immediately another demonic nation declares war, or he declares war—both of them are finished. This is going on.