Mīmāṃsā and Vedanta consider vedas too be eternal and **authoress**. But if a book exists it must have an author. And what is the source of vedas according to these schools. They don't even believe vedas are authored by the God. [Source](https://hinduism.stackexchange.com/a/44487/22556) 

The author of the Vedas should either be God or humans.

My questions : **How can vedas be authorless**? 

**And what is the source(if they are authorless) of the Vedas according to these schools**?