If this comes as a shocker to you, then I should be the one to enquire as to how you managed to stay blind in the face of the obvious.
Just strike up a discussion on some complex topic, and you can see many people resort to "because the author here in this book said" or "we are taught so and so".
A first principles reasoning can show you the steps that lead to a specific conclusion without invoking any author, teacher or course.
Cheers. Hope it helps.