“Then, I have two more things to explain to you. The fourth dimension is just as much _here_ as anywhere else. Right here around you and me things exist and go forward in the fourth dimension; but we do not see them and are not conscious of them, because we are confined to our own three. Secondly: if we name the four coordinates as Einstein does, _x_, _y_, _z_, and _t_, then we exist in _x_, _y_, and _z_, and move freely about in them; but are powerless to move in _t_. Why? Because _t_ is the time dimension; and the time dimension is a difficult one for biological structures that depend on irreversible chemical reactions for their existence. But, biochemical reactions can take place along any one of the other dimensions as well as along _t_. “Therefore, let us transform coordinates. Rotate the property of chemical irreversibility from _t_ to _z_. Since we are organically able to exist (or at least to perceive) in only three dimensions at once, our new time dimension will be _z_. We shall be unconscious of _z_ and cannot travel in it. Our activities and consciousness will take place along _x_, _y_, and _t_. “According to fiction writers, to switch into the _t_ dimension, some sort of an apparatus with an electrical field ought to be necessary. It is not. You need nothing more to rotate into the _t_ dimension than you do to stop the moon and make the trees move as you ride down the road; or than you do to turn the cubes upside down. It is a matter of _relativity_.” I had ceased trying to wonder or to understand. “Show me!” was all I could gasp. “The success of this experiment in changing from the _z_ to the _t_ coordinate has depended largely upon my lucky discovery of a favorable location. It is just as, when you want the moon to ride the tree tops successfully, there have to be favorable features in the topography or it won’t work. The edge of this building and that little walk between the two rows of Norway poplars seems to be an angle between planes in the _z_ and _t_ dimensions. It seems to slope downwards, does it not?--Now walk from here to the end and imagine yourself going upwards. That is all. Instead of feeling this building behind and _above_ you, conceive it as behind and _below_. Just as on your ride by moonlight, you must tell yourself that the moon is not moving while the trees ride by--Can you do that? Go ahead then.” He spoke in a confident tone, as though he knew exactly what would happen.