When, from a family circle, one of its members emigrates into "high society"—which to him appears a feat without parallel until after the lapse of a decade he observes that it has been performed in other ways and for different reasons by more than one of the men whom he knew as boys—he draws round about himself a zone of shadow, a terra incognita, which is clearly visible in its minutest details to all those who inhabit it with him, but is darkest night and nothingness to those who may not penetrate it but touch its fringe without the least suspicion of its existence in their midst.