Rhubarb, that harbinger of spring for many, is honored in the United States on January 23rd with National Rhubarb Day. Having let National Rhubarb Vodka Day (first Saturday in December) pass without note, I wanted to bake a pie in preparation. Thanks to the generosity of a neighbor and his bountiful garden last spring and summer, I had plenty set by. Rhubarb does freeze well. Inspired by the scholars transcribing, as well as cooking with and blogging about, culinary manuscripts dating from 1600 to 1800 in the University of Pennsylvania collections (recently profiled in The Washington Post), I turned to the Smithsonian Libraries for my commemorative effort.