In the Mandukya Upanishad The Non Dual Sages who wrote The Upanishads 3000 years ago explained the difference between Who You Think You Are: The Mind and Who You Really Are:
The Witness/Awareness/Consciousness better than any other mortal beings.
Only Ascended Master Jesus explains it better (in The Way of Mastery).
But if you have a materialist hang up about channelled teachings, the Upanishadic Sages should be your go to.
This is my favourite Modern day Non Dual Sage: Swami Sarvapriananda