to explain one
or two misconceptions. But he is not the Square he once was. Years of
imprisonment, and the still heavier burden of general incredulity and
mockery, have combined with the thoughts and notions, and much also of
the terminology, which he acquired during his short stay in spaceland.
He has, therefore, requested me to reply in his behalf to two special
objections, one of an intellectual, the other of a moral nature.

The first objection is, that a Flatlander, seeing a Line, sees
something that must be THICK to the eye as well as LONG to the eye
(otherwise it would not be visible, if it had not some thickness); and
consequently he ought (it is argued) to acknowledge that his countrymen
are not only long and broad, but also (though doubtless to a very
slight degree) THICK or HIGH. This objection is plausible, and, to
Spacelanders, almost irresistible, so that, I confess, when I first
heard it, I knew not what to reply. But my poor old friend's answer
appears to me completely to meet it.

"I admit," said he--when I mentioned to him this objection--"I admit
the truth of your critic's facts, but I deny his conclusions. It is
true that we have really in Flatland a Third unrecognized Dimension
called 'height,' just as it also is true that you have really in
Spaceland a Fourth unrecognized Dimension, called by no name at
present, but which I will call 'extra-height.' But we can no more take
cognizance of our 'height' than you can of your 'extra-height.' Even
I--who have been in Spaceland, and have had the privilege of
understanding for twenty-four hours the meaning of 'height'--even I
cannot now comprehend it, nor realize it by the sense of sight or by
any process of reason; I can but apprehend it by faith.

"The reason is obvious. Dimension implies direction, implies
measurement, implies the more and the less. Now, all our lines are
EQUALLY and INFINITESIMALLY thick (or high, whichever you like);
consequently, there is nothing in them to lead our minds to the
conception of that Dimension. No 'delicate micrometer'--as has been
suggested by one too hasty Spaceland critic--would in the least avail
us; for we should not know WHAT TO MEASURE, NOR IN WHAT DIRECTION.
When we see a Line, we see something that is long and BRIGHT;
BRIGHTNESS, as well as length, is necessary to the existence of a Line;
if the brightness vanishes, the Line is extinguished. Hence, all my
Flatland friends--when I talk to them about