Introduction

The Time Traveller (for so it will be convenient to speak of him) was expounding a recondite matter to us. His grey eyes shone and twinkled, and his usually pale face was flushed and animated. The fire burnt brightly, and the soft radiance of the incandescent lights in the lilies of silver caught the bubbles that flashed and passed in our glasses. Our chairs, being his patents, embraced and caressed us rather than submitted to be sat upon, and there was that luxurious after-dinner atmosphere, when thought runs gracefully free of the trammels of precision. And he put it to us in this way—marking the points with a lean forefinger—as we sat and lazily admired his earnestness over this new paradox (as we thought it) and his fecundity.

The Time Traveller was explaining a difficult subject to us. We will call him the Time Traveller for convenience. His grey eyes shone and twinkled, and his usually pale face was flushed and lively. The fire burned brightly. The soft glow of electric lights in silver lilies caught the bubbles flashing and disappearing in our glasses. Our chairs were his patented designs. They hugged and caressed us rather than merely letting us sit on them. The room had that luxurious after-dinner atmosphere, when thoughts flow freely without the restraints of precision. And he explained his idea like this, marking each point with a thin forefinger. We sat lazily admiring his earnestness about this new paradox, as we thought it was, and his wealth of ideas.

“You must follow me carefully. I shall have to controvert one or two ideas that are almost universally accepted. The geometry, for instance, they taught you at school is founded on a misconception.”

“You must follow me carefully. I will have to challenge one or two ideas that are almost universally accepted. For example, the geometry you learned at school is based on a misunderstanding.”

“Is not that rather a large thing to expect us to begin upon?” said Filby, an argumentative person with red hair.

“Isn’t that rather a lot to expect us to start with?” said Filby, an argumentative man with red hair.

“I do not mean to ask you to accept anything without reasonable ground for it. You will soon admit as much as I need from you. You know of course that a mathematical line, a line of thickness nil, has no real existence. They taught you that? Neither has a mathematical plane. These things are mere abstractions.”

“I’m not asking you to accept anything without good reason. You’ll soon agree to as much as I need you to. You know, of course, that a mathematical line, with zero thickness, has no real existence. You were taught that, weren’t you? A mathematical plane has no real existence either. These things are only abstract concepts.”

“That is all right,” said the Psychologist.

“That’s all right,” said the Psychologist.

“Nor, having only length, breadth, and thickness, can a cube have a real existence.”

“Nor can a cube really exist with only length, width, and thickness.”

“There I object,” said Filby. “Of course a solid body may exist. All real things—”

“I disagree there,” said Filby. “Of course a solid body may exist. All real things...”

“So most people think. But wait a moment. Can an instantaneous cube exist?”

“That’s what most people think. But wait a moment. Can an instantaneous cube exist?”

“Don’t follow you,” said Filby.

“I don’t understand you,” said Filby.

“Can a cube that does not last for any time at all, have a real existence?”

“Can a cube that lasts for no time at all really exist?”

Filby became pensive. “Clearly,” the Time Traveller proceeded, “any real body must have extension in four directions: it must have Length, Breadth, Thickness, and—Duration. But through a natural infirmity of the flesh, which I will explain to you in a moment, we incline to overlook this fact. There are really four dimensions, three which we call the three planes of Space, and a fourth, Time. There is, however, a tendency to draw an unreal distinction between the former three dimensions and the latter, because it happens that our consciousness moves intermittently in one direction along the latter from the beginning to the end of our lives.”

Filby grew thoughtful. “Clearly,” the Time Traveller continued, “any real body must extend in four directions: Length, Breadth, Thickness, and Duration. But a natural weakness of the human body leads us to overlook this fact. I will explain that weakness in a moment. There are really four dimensions. We call three of them the three planes of Space, and the fourth is Time. Yet we tend to make a false distinction between the three dimensions of Space and the dimension of Time. We make this distinction because our consciousness moves at intervals in one direction through Time, from birth to death.”

“That,” said a very young man, making spasmodic efforts to relight his cigar over the lamp; “that . . . very clear indeed.”

“That,” said a very young man. He was making jerky attempts to relight his cigar over the lamp. “That . . . very clear indeed.”

“Now, it is very remarkable that this is so extensively overlooked,” continued the Time Traveller, with a slight accession of cheerfulness. “Really this is what is meant by the Fourth Dimension, though some people who talk about the Fourth Dimension do not know they mean it. It is only another way of looking at Time. There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it. But some foolish people have got hold of the wrong side of that idea. You have all heard what they have to say about this Fourth Dimension?”

“Now, it is very remarkable that so many people overlook this,” continued the Time Traveller, sounding slightly more cheerful. “Really, this is what the Fourth Dimension means. Though some people who talk about the Fourth Dimension do not know that this is what they mean. It is simply another way of looking at Time. There is no difference between Time and any of the three dimensions of Space, except that our consciousness moves along Time. But some foolish people have misunderstood that idea. You have all heard what those people have to say about this Fourth Dimension?”

“I have not,” said the Provincial Mayor.

“I haven’t,” said the Provincial Mayor.

“It is simply this. That Space, as our mathematicians have it, is spoken of as having three dimensions, which one may call Length, Breadth, and Thickness, and is always definable by reference to three planes, each at right angles to the others. But some philosophical people have been asking why three dimensions particularly—why not another direction at right angles to the other three?—and have even tried to construct a Four-Dimensional geometry. Professor Simon Newcomb was expounding this to the New York Mathematical Society only a month or so ago. You know how on a flat surface, which has only two dimensions, we can represent a figure of a three-dimensional solid, and similarly they think that by models of three dimensions they could represent one of four—if they could master the perspective of the thing. See?”

“It is simply this. Our mathematicians describe Space as having three dimensions, which we may call Length, Breadth, and Thickness. Space can always be defined using three planes, each at right angles to the others. But some philosophically minded people have been asking why there are three dimensions in particular. Why not another direction at right angles to the other three? They have even tried to develop a Four-Dimensional geometry. Professor Simon Newcomb was explaining this idea to the New York Mathematical Society only a month or so ago. You know how we can draw a three-dimensional solid on a flat surface, which has only two dimensions. Similarly, these thinkers believe they could use three-dimensional models to represent a four-dimensional solid, if they could master its perspective. See?”

“I think so,” murmured the Provincial Mayor; and, knitting his brows, he lapsed into an introspective state, his lips moving as one who repeats mystic words. “Yes, I think I see it now,” he said after some time, brightening in a quite transitory manner.

“I think so,” murmured the Provincial Mayor. He frowned and sank into thought, his lips moving as if he were repeating mystical words. “Yes, I think I see it now,” he said after a while, brightening only briefly.

“Well, 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.”

“Well, I don’t mind telling you I’ve been working on the 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. Here are others at fifteen, seventeen, twenty-three, and so on. All these portraits are clearly slices, so to speak, showing his four-dimensional being in three dimensions. His four-dimensional being is fixed and cannot change.”

“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 recognised? But certainly it traced such a line, and that line, therefore, we must conclude, was along the Time-Dimension.”

“Scientists,” the Time Traveller continued, after a pause to let his listeners fully absorb his point, “know very well that Time is only a kind of Space. Here is a familiar scientific chart, a weather record. The line I’m tracing with my finger shows changes in the barometer reading. Yesterday the reading was this high. Last night it fell, then this morning it rose again, and continued gently upward to here. Surely the mercury did not trace this line in any of the generally recognized dimensions of Space? But the mercury certainly traced such a line. We must therefore conclude that the line ran 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?”

“But,” said the Medical Man. He stared hard at a coal in the fire. “If Time is really just a fourth dimension of Space, why do we see Time as something different? And why have we always seen Time that way? And why can't we move through Time as we move through the other dimensions of Space?”

The Time Traveller 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 how about up and down? Gravitation limits us there.”

The Time Traveller smiled. “Are you so sure we can move freely in space? We can move left and right, backward and forward freely enough, and people have always done so. I admit we move freely in two dimensions. But what about up and down? Gravity limits us there.”

“Not exactly,” said the Medical Man. “There are balloons.”

“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.”

“But before balloons, people could not move freely up or down, except by occasionally jumping or crossing uneven ground.”

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

“But they could still move up and down a little,” said the Medical Man.

“Easier, far easier down than up.”

“Easier, much easier to go down than up.”

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

“And you cannot move through Time at all. You cannot escape 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.”

“My dear sir, that is exactly where you are wrong. That is exactly where the whole world has gone wrong. We are always moving away from the present moment. Our minds have no physical substance or dimensions. They move along the Time-Dimension at a constant speed from birth to death. Just as we would travel down if we began our lives fifty miles above the earth’s surface.”

“But the great difficulty is this,” interrupted the Psychologist. “You can move about in all directions of Space, but you cannot move about in Time.”

“But here’s the main difficulty,” interrupted the Psychologist. “You can move in all directions in Space, but you cannot move around in Time.”

“That is the germ of my great discovery. But you are wrong to say that we cannot move about in Time. For instance, if I am recalling an incident very vividly I go back to the instant of its occurrence: I become absent-minded, as you say. I jump back for a moment. Of course we have no means of staying back for any length of Time, any more than a savage or an animal has of staying six feet above the ground. But a civilised man is better off than the savage in this respect. He can go up against gravitation in a balloon, and why should he not hope that ultimately he may be able to stop or accelerate his drift along the Time-Dimension, or even turn about and travel the other way?”

“That is the seed of my great discovery. But you are wrong to say that we cannot move around in Time. For example, if I recall an event very vividly, I go back to the moment it happened. I become absent-minded, as you call it. I jump back for a moment. Of course, we have no way of staying back for any length of Time. Neither can a savage or an animal stay six feet above the ground. But a civilised man has an advantage over the savage in overcoming such limits. He can rise against gravity in a balloon. So why should he not hope to one day stop or speed up his drift along the Time-Dimension? Or even turn around and travel the other way?”

“Oh, this,” began Filby, “is all—”

“Oh, this,” Filby began, “is all...”

“Why not?” said the Time Traveller.

“Why not?” said the Time Traveller.

“It’s against reason,” said Filby.

“It’s not logical,” said Filby.

“What reason?” said the Time Traveller.

“What reason?” asked the Time Traveller.

“You can show black is white by argument,” said Filby, “but you will never convince me.”

“You can argue that black is white,” said Filby, “but you will never convince me.”

“Possibly not,” said the Time Traveller. “But now you begin to see the object of my investigations into the geometry of Four Dimensions. Long ago I had a vague inkling of a machine—”

“Possibly not,” said the Time Traveller. “But now you’re beginning to see why I’ve been studying the geometry of Four Dimensions. Long ago, I had a vague idea for a machine...”

“To travel through Time!” exclaimed the Very Young Man.

“Travel through Time!” the Very Young Man exclaimed.

“That shall travel indifferently in any direction of Space and Time, as the driver determines.”

“That will travel equally well in any direction in space and time, as the driver chooses.”

Filby contented himself with laughter.

Filby did nothing but laugh.

“But I have experimental verification,” said the Time Traveller.

“But I have proof from experiments,” said the Time Traveller.

“It would be remarkably convenient for the historian,” the Psychologist suggested. “One might travel back and verify the accepted account of the Battle of Hastings, for instance!”

“Time travel would be incredibly useful for historians,” the Psychologist suggested. “Someone could go back and check the accepted account of the Battle of Hastings, for example!”

“Don’t you think you would attract attention?” said the Medical Man. “Our ancestors had no great tolerance for anachronisms.”

“Don’t you think you would attract attention?” said the Medical Man. “Our ancestors had little tolerance for things that didn’t belong in their time.”

“One might get one’s Greek from the very lips of Homer and Plato,” the Very Young Man thought.

“You could learn Greek directly from Homer and Plato themselves,” the Very Young Man thought.

“In which case they would certainly plough you for the Little-go. The German scholars have improved Greek so much.”

“In that case, they would certainly fail you on the Little-go exam. German scholars have improved Greek so much.”

“Then there is the future,” said the Very Young Man. “Just think! One might invest all one’s money, leave it to accumulate at interest, and hurry on ahead!”

“Then there’s the future,” said the Very Young Man. “Just think! You could invest all your money, leave it to earn interest, and rush ahead into the future!”

“To discover a society,” said I, “erected on a strictly communistic basis.”

“To discover a society,” I said, “built on strictly communist principles.”

“Of all the wild extravagant theories!” began the Psychologist.

“Of all the wild, far-fetched theories!” the Psychologist began.

“Yes, so it seemed to me, and so I never talked of it until—”

“Yes, that’s how it seemed to me, so I never talked about it until...”

“Experimental verification!” cried I. “You are going to verify that?”

“Testing it with an experiment!” I cried. “You’re going to test that?”

“The experiment!” cried Filby, who was getting brain-weary.

“The experiment!” shouted Filby, who was getting mentally tired.

“Let’s see your experiment anyhow,” said the Psychologist, “though it’s all humbug, you know.”

“Let’s see your experiment anyway,” said the Psychologist, “though it’s all nonsense, you know.”

The Time Traveller smiled round at us. Then, still smiling faintly, and with his hands deep in his trousers pockets, he walked slowly out of the room, and we heard his slippers shuffling down the long passage to his laboratory.

The Time Traveller smiled at us all. Then, still smiling faintly, he walked slowly out of the room with his hands deep in his trouser pockets. We heard his slippers shuffling down the long hallway to his laboratory.

The Psychologist looked at us. “I wonder what he’s got?”

The Psychologist looked at us. “I wonder what he has?”

“Some sleight-of-hand trick or other,” said the Medical Man, and Filby tried to tell us about a conjuror he had seen at Burslem, but before he had finished his preface the Time Traveller came back, and Filby’s anecdote collapsed.

“Some kind of sleight-of-hand trick,” said the Medical Man. Filby tried to tell us about a magician he had seen at Burslem. But before he could finish his introduction, the Time Traveller returned, and Filby’s story fell flat.