, I do not mind telling you I have been at work upon this
geometry of Four Dimensions for some time. Some of my results
are curious. For instance, here is a portrait of a man at eight
years old, another at fifteen, another at seventeen, another at
twenty-three, and so on. All these are evidently sections, as it
were, Three-Dimensional representations of his Four-Dimensioned
being, which is a fixed and unalterable thing.

'Scientific people,' proceeded the Time Traveller, after the pause
required for the proper assimilation of this, 'know very well that
Time is only a kind of Space. Here is a popular scientific diagram,
a weather record. This line I trace with my finger shows 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 in Time as we move about in the other dimensions of Space?'

The Time Traveller smiled. 'Are you 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 how about up and down? Gravitation limits us there.'

'Not exactly,' said the Medical Man. 'There are balloons.'

'But before the balloons, save for spasmodic jumping and the
inequalities of the surface, man had no freedom of vertical
movement.'

'Still they could move a little up and down,' said the Medical Man.

'Easier, far easier down than up.'

'And you cannot move at all in Time, you cannot get away from the
present moment.'

'My dear sir, that is just where you are wrong. That is just where
the whole world has gone wrong. We are always getting away from the
present moment. Our mental existences, which are immaterial and have
no dimensions, are passing along the Time-Dimension with a uniform
velocity from the cradle to the grave. Just as we should travel _down_
if we began our existence fifty miles above the earth's surface.'

'But the great difficulty is this,' interrupted the Psychologist.
'You _can_ move ab