the movement of the barometer. Yesterday it was so high, yesterday night it fell, then this morning it rose again, and so gently upward to here. Surely the mercury did not trace this line in any of the dimensions of space generally recognized? But certainly it traced such a line, and that line, therefore, we must conclude, was along the Time Dimension."
"But," said the Medical Man, staring hard at a coal in the fire, "if Time is really only a fourth dimension of Space, why is it, and why has it always been, regarded as something different? And why cannot we move about in Time as we move about in the other dimensions of Space?"
The Philosophical Person smiled. "Are you so sure we can move freely in Space? Right and left we can go, backward and forward freely enough, and men always have done so. I admit we move freely in two dimensions. But now about up and down? Gravitation limits us there."