God's systematic incarnations maintain cosmic order and offer liberation through knowledge of His transcendental nature.Listen — Srila Prabhupada Uvaca
Prabhupāda: avatāra haya kṛṣṇera ṣaò-vidha prakāra puruṣāvatāra eka, līlāvatāra āra [Cc Madhya 20.245] [There are six types of incarnations [avatāras] of Kṛṣṇa. One comprises the incarnations of Viṣṇu [puruṣa-avatāras], and another comprises the incarnations meant for the performance of pastimes [līlā-avatāras]] guṇāvatāra, āra manvantarāvatāra yugāvatāra, āra śaktyāveśāvatāra [Cc Madhya 20.246] [There are incarnations that control the material qualities [guṇa-avatāras], incarnations associated with the reign of each Manu [manvantara-avatāras], incarnations in different millenniums [yuga-avatāras] and incarnations of empowered living entities [śaktyāveśa-avatāras]] Now, we have been discussing about incarnations. These incarnations are concerned so far the maintenance of the material world is required. In the spiritual world there is no incarnation.
There is a permanent situation of the spiritual planets, and in different planets, He, Kṛṣṇa, has different expansions under different symbolic representation, and they are differently named. There is no change. But in the material world, when we speak of incarnation, that is in relationship with this material world. In this... For the material world these incarnations are expanded.
And what are they? First the puruṣāvatāra; then līlāvatāra; then guṇāvatāra, three; then manvantarāvatāra, four; then yugāvatāra, five; and then śaktyāveśāvatāra. Śaktyāveśāvatāra. So these incarnations are manifested at different times according to the need. Just like in the Bhagavad-gītā it is stated, yadā yadā hi dharmasya glānir bhavati bhārata abhyutthānam adharmasya tadātmānaṃ sṛjāmy aham [Bg 4.7] [Whenever and wherever there is a decline in religious practice, O descendant of Bharata, and a predominant rise of irreligion—at that time I descend Myself.] 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]: [This material nature is working under My direction, O son of Kuntī, and it is producing all moving and unmoving beings. By its rule this manifestation is created and annihilated again and again.] "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.