But of the nature of 'things-in-themselves,' of what may exist at the other end of our system of telephone wires, we know nothing at all.
"But the reader, perhaps, remarks, 'I not only see an object, but I can _touch_ it.

I can trace the nerve from the tip of my finger to the brain.

I am not like the telephone clerk, I can follow my network of wires to their terminals and find what is at the other end of them.' Can you, reader?
Think for a moment whether your _ego_ has for one moment got away from his brain exchange.

The sense-impression that you call touch was just as much as sight felt only at the brain end of a sensory nerve.

What has told you also of the nerve from the tip of your finger to your brain?
Why, sense-impressions also, messages conveyed along optic or tactile sensory nerves.