It was a long debate spanning several years. Some important bits, relevant to the topic, are here:

https://medium.com/@jackprestonking/or-as-castaneda-put-it-they-gave-us-their-mind-4b511dd18bc2

And it gets completely explicit here:

https://medium.com/@jackprestonking/the-representation-of-the-whole-universe-is-within-your-brain-generated-mind-argument-is-the-ad7462416203

The first link also contains links to Jack's website where you can read more about his ideas.