Pain woke me in the middle of the night. It flattened me to the mattress. I lay still, certain that if I moved, my head would not move with me. It would simply snap from my neck, a lead weight of agony too heavy for my body to support. I’m not given to migraines, but this headache, so intense the nausea began in my toes and roiled through my limbs, was something organic, alive, beyond the reach of medication or meditation. I barely slept, and at four a.m. I gave myself up to the inevitable.    As soon as I opened the front door to unhitch a hanging plant whirling in the sudden wind, I knew. Overnight, the gray silk of Autumn had slipped in, running cool fingers through Summer’s sun-bleached hair…