You sit down to meditate. The instruction is to watch your thoughts. You watch. Thoughts come. Thoughts go. There's the watching. There's the watcher. Or so it seems. Now ask what the watcher is made of. The watcher isn't a blank, neutral observer. The watcher prefers some thoughts and dislikes others. The watcher has tastes. The watcher labels and judges. Those tastes and labels — where did they come from?
K's answer: the watcher is composed of yesterday. Every preference, every judgment, every category the "watcher" brings to the watching is a deposit from the past. The watching looks fresh. It isn't. It's the past, watching the present, through filters built earlier.
This is how the observer-is-the-observed claim deepens. Not only is there no separate "I" watching the anger. The watching itself is colored, throughout, by what the "I" has accumulated. There's no neutral position. There's only past, looking at present, and pretending to be separate from it.
If you've ever caught yourself watching another person and noticing how much your reaction was about you — your fear, your envy, your wound — you've felt this. The "objective" read of someone else was always laced with your inheritance. The neutral observer was never neutral.
Whatever's doing the watching right now isn't fresh. It's yesterday, dressed up as right-now. The seeing K pointed to is the seeing without yesterday in it. That's not the watcher. That's something else.