THE EARLY SUN’S performance was indifferent on its own, but the abundant yellow leaves amplified it into something passable. Then flat gray took over the sky, with dark pigeons wheeling around and around against it. The bins of sweaters and flannel shirts shifted uncontrollably under examination and started to plunge from the top shelf. Jackets were zipped and hoods were up, and the midafternoon light was dull and wintry, though the air still felt damper than real autumn. Little roundish acorns, pale where their caps had been, dotted the sidewalk and clustered on top of a drain. Sitting outside grew intolerable somewhere between 10 minutes and 20. The clouds thinned again to blue, and a little bit of the luster came back, this time with a new sharpness to the air.