Śrīmad-Bhāgavatam 1.18.37

Thus the beginning of the misuse of brahminical power began, and gradually the brāhmaṇas in the age of Kali became devoid of both brahminical powers and culture. The brāhmaṇa boy considered Mahārāja Parīkṣit to be kulāṅgāra, or the wretched of the dynasty, but factually the brāhmaṇa boy himself was so because only from him did the brāhmaṇa caste become powerless, like the snake whose poisoned teeth are broken. The snake is fearful as long as his poison teeth are there, otherwise he is fearful only to children. The personality of Kali conquered the brāhmaṇa boy first, and gradually the other castes. Thus the whole scientific system of the orders of society in this age has assumed the form of a vitiated caste system, which is now being uprooted by another class of men similarly influenced by the age of Kali. One should see to the root cause of vitiation and not try to condemn the system as it is, without knowledge of its scientific value.