T ALL BEGAN with a sofa. A passionate collector of Early American furniture had acquired a very rare and beautiful double-peak sofa at auction and wanted to know how to reupholster it. An ardent young decorator with a comprehensive knowledge of classic American furnishings had seen this sofa earlier and had become intrigued by the idea of finding the perfect fabric to cover it. It was inevitable that these two men would meet and that, as so often happens when an artists finds his ideal patron, a productive working relationship begin. The collector and his wife (he is a partner in a financial management firm, she is a museum docent) live in a 1930s center-hall Colonial in Westchester Couty, New York. For years they had been buying ancient Indian and Himalayan art, and furniture in the late Federal style. They had become attracted to the graceful silhouettes of earlier American furniture; and though they had a world-class collection, they didn't know how to showcase it. Enter decorator Thomas Jayne, a veteran of Winterthur, the Cooper Hewitt, and Christie's (not to mention Parish-Hadley), who had just returned from London with some knockout period-style fabrics and trims. He knew just how the Philadelphia double-peak sofa should be reupholstered: not in silk damask but in the more historically accurate wool damask. He envisioned handmade silk tufts to embellish the horsehair mattress. He envisioned a subtle shade of pink instead of the more traditional red.   AS IF THE BOTTLES of Chateau d'Yguem and the 18th-century important English silver salvers, top left, weren't appetizing enough, the dining room boasts a triple-pedestal American dining table (one of three extant), these pages, once owned by the Livingston family; an inlaid William Lloyd sideboard; and Thomas B. Way, painted by Bard. The Bardith plates may be fragile, but the modern silk squabs, with mattress tufting, on the late 18th-century English chairs are sturdy enough to withstand the stresses of daily family use. continued on next page