Isobel went to Mexico with her uncle and there had a most interesting time. She studied Aztec history with her usual thoroughness; so well, indeed, that she became a recognised authority on the subject. She climbed Popocatepetl, the mysterious “Sleeping Woman” that overhangs the ancient town, and looked into its crater. Greatly daring, she even visited Yucatan and saw some of the pre-Aztec remains. For this adventure she paid with an attack of fever which never quite left her system. Indeed, that fever had a peculiar effect upon her, which may have been physical or something else. Isobel’s fault, or rather characteristic, as the reader may have gathered, was that she built too much upon the material side of things. What she saw, what she knew, what her body told her, what the recorded experience of the world taught—these were real; all the rest, to her, was phantasy or imagination. She kept her feet upon the solid ground of fact, and left all else to dreamers; or, as she would have expressed it, to the victims of superstition inherited or acquired. Well, something happened to her at the crisis of that fever, which was sharp, and took her on her return from Yucatan, at a horrible port called Frontera, where there were palm trees and _zopilotes_—a kind of vile American vulture—which sat silently on the verandah outside her door in the dreadful little hotel built upon piles in the mud of the great river, and mosquitoes by the ten million, and sleepy-eyed, crushed-looking Indians, and horrible halfbreeds, and everything else which suggests an earthly hell, except the glorious sunshine. Of a sudden, when she was at her worst, all the materiality—if there be such a word—which circumstances and innate tendency had woven about her as a garment, seemed to melt away, and she became aware of something vast in which she floated like an insect in the atmosphere—some surrounding sea which she could neither measure nor travel. She knew that she was not merely Isobel Blake, but a part of the universe in its largest sense, and that the universe expressed itself in miniature within her soul. She knew that ever since it had been, she was, and that while it existed she would endure. This imagination or inspiration, whichever it may have been, went no further than that, and afterwards she set it down to delirium, or to the exaltation that often accompanies fever. Still, it left a mark upon her, opening a new door in her heart, so to speak.