— and so on

That is to say, I no longer thought of the matter itself, but only of what I was thinking about it. If I had then asked myself, “Of what am I thinking?” the true answer would have been, “I am thinking of what I am thinking;” and if I had further asked myself, “What, then, are the thoughts of which I am thinking?” I should have had to reply, “They are attempts to think of what I am thinking concerning my own thoughts” — and so on.

Leo Tolstoy – Boyhood (1854)


I think Tolstoy was wrong. Ignoring mental images, when we think, we talk to ourselves without speaking. We do it and are aware of doing it, but that’s it. By making it into a series of levels Tolstoy was playing with words. 

Of course he was a young man when he wrote this, perhaps fascinated by the possibilities we seem to see in words. As we know, it's still a problem today. Net Zero is an example.