A calligraphy brush can be rotated between your fingers when writing the curves in Chinese characters on paper. It’s hard to do this though when you’re cutting an inscription into the side of your seal stone. A seal carving knife can’t be turned easily because it’s difficult to both rotate the knife while, at the same time, apply enough pressure to cut into the stone. In fact, it can be dangerous as it can cause your blade to slip. So there are two options for carving characters into the side of the stone: one is to rotate your hand at the wrist or your arm at the elbow—which can result in odd cutting angles, or you can rotate the stone—cutting the characters sideways or even upside down. I’ve seen seal carvers use both methods. Use what works best for you.