_something_ in Phrenology. A broad, high forehead, it is commonly
agreed, promises intellect; one that is "villainous low," and has a
huge hind-head back of it, is wont to mark an animal nature. I have as
rarely met an unbiased and sensible man who really believed in the
bumps. It is observed, however, that persons with what the
phrenologists call "good heads" are more prone than others
toward plenary belief in the doctrine.

It is so hard to prove a negative that, if a man should assert that
the moon was in truth a green cheese, formed by the coagulable
substance of the Milky Way, and challenge me to prove the contrary, I
might be puzzled. But if he offer to sell me a ton of this lunar
cheese, I call on him to prove the truth of the caseous nature of our
satellite before I purchase.

It is not necessary to prove the falsity of the phrenological
statement. It is only necessary to show that its truth is not proved,
and cannot be, by the common course of argument. The walls of the
head are double, with a great air-chamber between them, over the
smallest and most closely crowded "organs." Can you tell how much
money there is in a safe, which also has thick double walls, by
kneading its knobs with your fingers? So when a man fumbles about my
forehead, and talks about the organs of _Individuality_, _Size_, etc.,
I trust him as much as I should if he felt of the outside of my
strongbox and told me that there was a five-dollar or a ten-dollar
bill under this or that particular rivet. Perhaps there is; _only he
doesn't know anything about it_. But this is a point that I, the
Professor, understand, my friends, or ought to, certainly, better than
you do. The next argument you will all appreciate.