It was strange, how easy it was to step right out of your own life, right out of the familiar Earth into cosmic mystery! As easy, Birrel was to think later, as opening a door.... As Birrel walked into his 71st Street apartment, snapping on the light and pocketing his keys, he suddenly stopped, tense with surprise. A man he had never seen before stood facing him. A commonplace-looking man with a gray hat, gray suit, and a grayish, young-middle-aged face. His voice was mild as he said, "Ross Birre