When you wake up in the morning, you may notice that by the time you realize you're thinking,
you're already being thought.
Thoughts just appear.
You're not doing them.
Wherever you go, whomever you're with, the voice in your head goes with you, whispering, nagging, enticing, judging, chattering, shaming, guilt-tripping, or yelling at you.
Most people think that they are what their thoughts tell them they are.
One day I noticed that I wasn't breathing—I was being breathed.
Then I also noticed, to my amazement, that I wasn't thinking—that I was actually being thought and that thinking isn't personal.
That voice in my head, isn't it me?
Don't I think my thoughts?
You can answer this for yourself.
If the voice in your head is you, who's the one listening to it?
Byron Katie, many quotes
Rumi, of course, put this whole discussion regarding the source of thought into wonderfully poetic terms.