st intelligent of detectives I went on
blindly over the traces of footprints which told me just no more than
they could.

"I came to the conclusion that I was a fool, lower in the scale of
intelligence than even the police of the modern romancer. Novelists
build mountains of stupidity out of a footprint on the sand, or from
an impression of a hand on the wall. That's the way innocent men are
brought to prison. It might convince an examining magistrate or the head
of a detective department, but it's not proof. You writers forget that
what the senses furnish is not proof. If I am taking cognisance of what
is offered me by my senses I do so but to bring the results within the
circle of my reason. That circle may be the most circumscribed, but if
it is, it has this advantage--it holds nothing but the truth! Yes, I
swear that I have never used the evidence of the senses but as servants
to my reason. I have never permitted them to become my master. They have
not made of me that monstrous thing,--worse than a blind man,--a man
who sees falsely. And that is why I can triumph over your error and your
merely animal intelligence, Frederic Larsan.

"Be of good courage, then, friend Rouletabille; it is impossible that
the incident of the inexplicable gallery should be outside the circle
of your reason. You know that! Then have faith and take thought with
yourself and forget not that you took hold of the right end when you
drew that circle in your brain within which to unravel this mysterious
play of circumstance.

"To it, once again! Go--back to the gallery. Take your stand on your
reason and rest there as Frederic Larsan rests on his cane. You will
then soon prove that the great Fred is nothing but a fool.

--30th October. Noon.

JOSEPH ROULETABILLE."

"I acted as I planned. With head on fire, I retraced my way to the
gallery, and without having found anything more than I had seen on
the previous night, the right hold I had taken of my reason drew me to
something so important that I was obliged to cling to it to save myself
from falling.

"Now for the strength and patience to find sensible traces to fit in
with my thinking--and these must come within the circle I have drawn
between the two bumps on my forehead!

--30th of October. Midnight."

"JOSEPH ROULETABILLE."

CHAPTER XIX. Rouletabille Invites Me to Breakfast at the Donjon Inn

It was not until later that Rouletabille sent me the note-book in which
he