MILAN — Miuccia Prada combined two seemingly contradictory themes in her beautiful spring collection for Prada, discretion of the up-to-date sort and the universal desire for decoration. The method she used was to team classic sweaters or pajama tops with pieces in rich Moroccan or Indian-style fabrics. Here, her little cardigan, contrast-piped shirt and ruffled brocade skirt. For more on the collections, see page 6.