The stream of new discoveries which followed Crookes's work justified his conviction that in cathode ray phenomena we have to do with a frontier region of physical nature. Still, the land that lies on the other side of this frontier is not the one Crookes had been looking for throughout his life. For, instead of finding the way into the land whither man's soul disappears at death, Crookes had inadvertently crossed the border into another land - a land which the twentieth-century scientist is impelled to call 'the country that is not ours'.