The Vineyard becomes a place of light in this season: the single candles in the windows of houses as dusk gathers along Island roads, the lights strung along the lines of a sailboat at Menemsha, the gorgeous multitude of white lights at the Dr. Daniel Fisher House in Edgartown, the colored lights strung around the evergreen trees — Christmas trees — occupying places of honor in hundreds of Vineyard homes. Even on a cloudy day, Vineyard Sound can shine like a luminescent opal, crossed by the bright white vessels of the Steamship Authority.