There is a system. In the process of this material world there is a system. Just like for maintenance of your State, United State, there is system of government, and there is an aim. Just like your government does not like that . . . there should be no . . . there should be no Communistic persons. And you write that "We trust in God." It is better to trust in God. You have got a system. Similarly, the maintenance of the whole material world, there is a system. It is not blind.
Foolish creatures, they think that everything has come out of nothing, and it is being managed by nature. No. Behind nature there is God. In the Bhagavad-gītā you have learned, mayādhyakṣeṇa prakṛtiḥ sūyate sa-carācaram (BG 9.10): "Under My superintendence the material nature is working." Material nature is not blind. Just like foolish person, because he cannot see President Johnson and the governmental personalities, they think, "It is going on. Nobody is there behind this government, and it is going on."
So similarly, 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.