George Kramer sat hunched on his stool behind the counter of the small hardware store on Coney Island Avenue, gazing out the window at the passing traffic. He was bundled up in a heavy sweater, a maroon wool cap folded above his ears. Toward the back of the store, beyond Mr. Kramer’s field of vision, Isaac Abraham was rifling through a cabinet. Mr. Abraham, the store’s owner for many years, knows Mr. Kramer about as well as anybody, and he was about to give a demonstration.