Mbh 12.59.3a

"'Bhishma said, "With concentrated attention, O tiger among kings, listen to it in detail as to how in the Krita age sovereignty first began. At first there was no sovereignty, no king, no chastisement, and no chastiser. All men used to protect one another righteously. As they thus lived, O Bharata, righteously protecting one another, they found the task (after some time) to be painful. Error then began to assail their hearts. Having become subject to error, the perceptions of men, O prince, came to be clouded, and thence their virtue began to decline. When their perceptions were dimmed and when men became subject to error, all of them became covetous, O chief of the Bharatas! And because men sought to obtain objects, which they did not possess, another passion called lust (of acquisition) got hold of them. When they became subject to lust, another passion, named anger, soon soiled them. Once subject to wrath, they lost all consideration of what should be done and what should not. Unrestrained sexual indulgence set in. Men began to utter what they chose. All distinctions between food that is clean and unclean and between virtue and vice disappeared. When this confusion set in amongst men, the Vedas disappeared. Upon the disappearance of the Vedas, righteousness was lost. When both the Vedas and righteousness were lost, the gods were possessed by fear. Overcome with fear, O tiger among men, they sought the protection of Brahmana. Having gratified the divine Grandsire of the universe, the gods, afflicted with grief, said unto him, with joined hands, 'O god, the eternal Vedas have been afflicted in the world of men by covetousness and error. For this, we have been struck with fear. Through loss of the Vedas, O Supreme Lord, righteousness also has been lost. For this, O Lord of the three worlds, we are about to descend to the level of human beings. Men used to pour libations upwards while we used to pour rain downwards.