To get the real sense of working in 3-D space, we must have movement. We can rotate our object around the vertical pole.

Notice how this movement defines a kind of plane (a flat surface) created by the intersecting yellow and green poles. We can imagine a flat plane, and the blue pole sticking out perpendicular to it. A line sticking out of a plane in this perpendicular way is said to be the "normal" of the plane. It's not too soon to learn this important word. It's part of the basic vocabulary of the 3-D artist.

We have been rotating the vertical axis. Now let's try turning the green axis, our original depth axis.

And finally, the original horizontal axis.

Take some time to get accustomed to these three different rotations. Hold the three images simultaneously on one screen and let them sink slowly into to your soul or subconscious (or whatever word you're comfortable with). This is, in the simplest form, the pure magic of 3-D computer graphics.