Incarnations: Direct and Indirect

Verse 1.3.5: Continuing the purport...
Here in the beginning, Srila Prabhupada is talking about Lord Siva. Lord Siva is a guna-avatara. This material world is created for living entities who have rebelled. This material nature is guided by the 3 modes of material nature. So the jiva's have to be impregnated in material nature, that is done by the glance of Maha Vishnu, which is Lord Siva. ..does not come in contact with material nature directly, He does it through Lord Siva.

So it is like milk and curd. Curd is also milk type, but it cannot be used in place of milk.

Next, Srila Prabhupada talks about the manu's. There are 14 manu's in one day of brahma. Right now, Vaivasvata Manvantara is going on. Actually in Bhagavad-gita, it is told that Krishna spoke the Bhagavad-gita first to Vivasvan, he then told it to manu.

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Then Srila Prabhupada writes about yuga cycles and the long span of a Manu.
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Krishna has all this incarnations and empowered incarnations only to bring us back to Godhead.