“It’s an investigation of our history, of our European past.” With that big idea in mind, Miuccia Prada sent out a focused collection of nipped-waist dresses, as well as tops and skirts in pleated burlap or silk, most of them layered with a low, hip-slung apron. Sometimes the fabrics were dotted with fraying holes, as if moths had descended and started munching en masse. Other times it looked as if spray-paint artists had gotten their hands on them, dipping the ridges of a pleated brown frock in a rusty red or scrawling graffiti squiggles across the front of a skirt