The major adjustment in our posture – Cheng Man-ching's great insight – is the Master's hand on the sacrum gently encouraging it down and forward. What this does, effectively, is suggest to the tail that it relax, unfurl, and take root. Over time – decades – the tail, so encouraged, becomes our tap root – our major source of energy from the earth. The legs, when they are used properly, are then two secondary supporting roots, not just supporting the spine from below but providing the impetus of the sacrum down and forward. For this the knees must work forward and out, away from the centre of the body, so that the top of the legs pinch the pelvis and squeeze energy upwards, like squeezing a tube of toothpaste. Dancers understand this because without it their spirit will not project.