“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 the unrecognized Dimension which is somehow visible in a Line—say, ‘Ah, you mean _brightness_’: and when I reply, ‘No, I mean a real Dimension,’ they at once retort, ‘Then measure it, or tell us in what direction it extends’; and this silences me, for I can do neither. Only yesterday, when the Chief Circle (in other words our High Priest) came to inspect the State Prison and paid me his seventh annual visit, and when for the seventh time he put me the question, ‘Was I any better?’ I tried to prove to him that he was ‘high,’ as well as long and broad, although he did not know it. But what was his reply? ‘You say I am “high”; measure my “high-ness” and I will believe you.’ What could I do? How could I meet his challenge? I was crushed; and he left the room triumphant.