From the minute your feet swing out of bed in the early gray light, your muscles begin a dance with what's below. Heel rolling, toes flexing, weight shifting from side to side, there's a subconscious push against what's underneath: carpet, wood, grass, dirt.
You spend your days walking upon the earth -- desk to chair, bedroom to kitchen, stairway to floor, one place to another -- with muscles stretching and pulling, each footfall pushing down then springing up from the solid ground. You are secure in the knowledge that you are strong. Your skeleton and muscles and nerve endings will work together. You are in control.
But then a day comes when you don't feel quite so strong. You are tired. You are sore. Instead of holding yourself against the earth, you let the earth hold you. Bones and muscles relax and sink downward, and you feel grateful that you are cradled by something larger, something much more expansive than your own will, your own might.