I'm not an expert on homelessness. I can't recite facts and figures about the issue without looking them up first. I haven't delved into the heaps of research about the subject by social scientists. My guess is that, among the true experts on homelessness, are the people who have actually lived on the streets day in and day out. Neal and George, for example, are two of the four men featured in my book, Homeless at Harvard, who've worn tread on Harvard Square's sidewalks for years, and have openly shared their stories.