I've always played with my left knee helping to support the weight of the bass, and as an orchestra teacher I've taught my beginners this position as well. The new book I'm using clearly instructs students that the belly is the only point of contact with the instrument, and that has kind of thrown me. I don't remember when or from whom I learned this position, but I've never even considered holding my bass any other way. It has always made sense to me to put as little weight on the left thumb as possible to facilitate left hand movement. I have always had lower back pain, though, and now I'm wondering if I'm just holding the bass wrong and this has contributed to my back pain. I understand there are different methods and schools of thought, but have I been teaching it wrong this whole time?