RustSKIPper
Hey Jane, I have only used a potters wheel a few times. When Clay is spinning it is like a wheel you put your finger(s) and hands around the piece at a radius from the center, and then clay becomes nearly perfectly circular. Your hands touch 100% of the circumference of the clay each time the wheel turns. You can let go of the pot, and it should stay right where it is, as long as you do not push off with one hand or something. It is a balance of circular motion and slight pressure that causes the clay to shape up. If you tried to do that with a still piece of clay, you would essentially have your hands in one spot, with no idea where the center of the clay is, pushing on the sides and leaving hand prints and pressure points. The wheel is dynamic, it turns much the same as a wood lathe, with a cutting tool on a piece of wood. You hold your fingers at a distance from the center, and all the clay will be at that same distance from the center. You can make pots on a table, but they will not be smooth and circular like the potting wheel. Simply because you are making use of a third dimension by using a wheel. It is like taking a compass and making a circle - versus trying to draw a circle free hand. The Free hand circle might be artistically pleasing to some, but the near perfect circular symmetry of having circles made for you is easier to get consistent wall thicknesses, without seams. You really should go to your local college and make an appointment with an art teacher, or go to a ceramics shop. Call them first, set up an appointment, and see first hand how it works - it is so much more informative to see it done, and to do it than it is to try to get me to describe it to you.