Visualising the fourth dimension--can it be done? Let's start with the second dimension. Can it be visualized? I believe so. It would not! appear as an infinitely thin vertical section of 'space' surrounded by void; rather, it should be visualized as a region where all objects appear to be 'horizontal' in nature. For example, a 2-D box should be correctly visualized as a horizontal region of 'brightness' (where the 2-D light is shining upon its surface), and directly underneath, a horizontal region of shadow (where the 2-D light source is not falling on the 2-D box). Turning left or right is meaningless--you'll still see the horizontal region of the side of the box the 2-D light falls on and it's shadowed part as if you never turned left or right. If you make a 180-degree turn, you see objects behind you--all as the horizontal 'smear' of the 2-D object you're looking at. A circle should appear as a horizontal smear who's height is equal to the height of the original circle, with its width extending from your left all the way to your right. The smear will have a smooth transition from bright (where the 2-D light falls upon the circle's surface) to dark (where no 2-D light falls upon it's surface). So as you can see, visualizing the 2-D is in itself somewhat of a mental challenge. But the fourth dimension? That dimension where the corner of your room will have not three but four folds coming from it, with each fold being at a 90-degree angle to the other three. Our three dimensions have three "folds" coming out of the corner: one for the ceiling, one for one wall and the last for the other wall. Can you visualize a 4-D region of space? If so, post your ideas here!