Persons who have no knowledge in the affairs of this material world, they think that, "This material nature is working, and automatically, by magic, the sun is coming out, the moon is coming out, and the season is changing, and everything is going on just like magic, and we are the master of everything." Never think . . . these foolish persons never think that they are not masters, they are servant, servant of the material nature. So that is their foolishness.
Therefore, when there is too much foolishness, so there is need of avatāra, incarnation, to correct. Yadā yadā hi dharmasya glānir bhavati. Whenever there is, I mean to say, discrepancies in the maintenance of law and order of this material nature, there is need of avatāra, incarnation. Because it is God's kingdom, it is also secondary kingdom—real kingdom in the spiritual world—so God comes in different avatāra.
And when the material world is created, the first avatāra is puruṣa-avatāra. The Mahā-Viṣṇu, Garbhodakaśāyī, They create. And then līlāvatāra. Līlāvatāra, under some particular circumstances, to save some particular devotee or to display some particular feature . . . just like Lord Rāma, He incarnated. He is līlāvatāra. Then guṇāvatāra. For maintenance of this material world there are different kinds of modes of nature, and to control those modes of nature there are avatāra: Brahmā, Viṣṇu, Maheśvara. Līlāvatāra. Then manvantarāvatāra. The changes of millenniums, that manvantarāvatāra. And then yugāvatāras, yugāvatāra, in each and every yuga. Just like this Kali-yuga. This is called Kali-yuga. In the Kali-yuga the incarnation is Lord Caitanya.