The exploration of these worse than Dædalian labyrinths is not unattended with danger. That intrepid investigator, Bosio, was several times well nigh lost in their mysterious depths. That disaster really happened to M. Roberts, a young French artist, whose adventure has been wrought into an exciting scene in Hans Andersen’s tale, “The Improvisatore,” and forms an episode in the Abbé de Lille’s poem, “_L’Imagination_.” Inspired by the enthusiasm of his profession, he attempted to explore one of the Catacombs, with nothing but a torch and a thread for a guide. As he wandered on through gallery and chamber, he became so absorbed in his study that, unawares, the thread slipped from his hand. On discovering his loss he tried, but in vain, to recover the clew. Presently his torch went out, and he was left in utter darkness, imprisoned in a living grave, surrounded by the relics of mortality. The silence was oppressive. He shouted, but the hollow 47 echoes mocked his voice. Weary with fruitless efforts to escape his dread imprisonment he threw himself in despair upon the earth, when, lo, something familiar touched his hand. Could he believe it? it was indeed the long lost clew by which alone he could obtain deliverance from this awful labyrinth. Carefully following the precious thread he reached at last the open air, And never Tiber, rippling through the meads, Made music half so sweet among its reeds; And never had the earth such rich perfume, As when from him it chased the odor of the tomb.[28]