I shall begin to tell you about this origin clearly,
but I cannot tell it as long as you think in common worldly ways.

What does it mean to return to the origin?

Turn your out turned worldly common thoughts in. Take a moment and be aware of your self-centered imagination (the voice of your mind).  With your eyes open keep watching your self-centered imagination until it settles and becomes quiet. Once quiet it has returned to its origin. Know and understand the  way the world is experienced from the point of view of your origin. That is what it means to return to the origin.