Many years ago, while taking an early spring walk near the University of Pittsburgh, I noticed a deep crack in the sidewalk, and within the crevice someone had wedged a lego action figure. I'd considered removing the toy as a keepsake of the first day outside after a brutal winter, but instead I allowed it to remain as a small part of the urban landscape. For several years, I took early spring walks along the same part of the city, and every year the lego man, a little more weathered, greeted me as an old acquaintance. Eventually, the city replaced the sidewalk, and like so many loose friendships, based on convenience and circumstance, the lego man was gone.