Verse 13

13.  The Atman, outward minded, Manifests the diversity of different mundane entities, as also those seen within the mind; thus does the Lord imagine.

"The Atman,  outward minded,  Manifests the diversity of different mundane entities"

The absolute described as outward minded means the Absolute manifesting this material Creation.
All entities are in reality diversifications of the same non dual Absolute,  is the meaning.

"as also those seen within the mind;"

"That"  (the Absolute)  that manifests all material forms seen as external to the mind,  also manifests the objects seen as within the mind.

"thus does the Lord imagine."

This  "imagination"  describes the Maya or the forgetting that the Absolute displays through projecting the play of Creation.
The Absolute assumes the roles of many and the consciousness of many.  The meaning is,  the Absolute is all that is.  The  "One"  is both the mind that imagines and the material object that is imagined as being external to the mind.