Good morning David!
Write the word "I" on a piece of paper. Look at the word, is that YOU?
At first I couldn't tell if it was me or not. Or rather, I couldn't for certain say it wasn't me. Then I noticed that it was the awareness of the word that was behind this uncertainty, in the sense that since I am aware of it I am part of it (or rather: it is part of me.)
The word "I" that I wrote on the paper is not the totality of me, but the sense that it is part of me lingers.
Speak the word “I” silently; be aware of any sensations or responses to this word. Are any of these reactions in your body or mind by themselves YOU?
Some tightness in the chest was experienced as I said the word I. The sensation itself is not me.
Now say the word “I” aloud. Is that sound YOU?
The sound is not me.
Is the combination of any of these, the word, the sound, the thought YOU?”
No, it seems impossible to combine them into a state where they are combined into something that is merged.
Is the thought, "I exist" you?
No, the thought is just hearing/seeing appearing in the mental field.
Is the thought "I" you?
Same here, it is just hearing/seeing appearing in the mental field, along with an intellectual concept.
Try to focus on your direct experience onto what is the medium into which those phenomena arrise and vanish.
Am I supposed to focus on the space?
I think I understand. In other words you are asking: "What are thoughts/sensation/Tom made of?"
//Tom