A rare street-fashion vignette, often observed on Fifth Avenue in Midtown, is a group of strangers, attracted by one another’s highly individual style of dress, who pause on their way to work to inquire of their clothes. The tradition may vanish, as one member of the group is moving to California. At times, they spontaneously try on one another’s look. Last week, nature provided a backdrop only it could create. In Central Park, a “Brigadoon” mist settled over the lake, and cascades of willows framed the Bow Bridge. All over the city, the ginkgo tree proved once again as the leaves fell that Manhattan streets are indeed paved with gold.