An excellent treatise.
I have to disagree with the quote above.
I have had more than one experience of knowing what someone else was thinking...relatives, friends and strangers.
We all have. But you knew I would state that.
You wrote you didn't like this, Jim; though you were inclined to be sympathetic with the statement of the argument "up 'til then".
When I read this piece for the first time, instantly (just as you did), I flashed on the problem of brain-to-brain trasnmission, as presently described by state-of-the-art science. Yet suffice it to say that presently the public record reports a vast variety of "brain experiences" that cannot be explained at all by present scientific methods.
Thinking the problem through further, the man did say "sign" is as valid a mode of communication as language, writing, et al. He hasn't shut the door on your concern at all.
I hope we can explore such questions on this thread, and that you would be willing to contribute your insights.