Certainly it would have been impossible to have invented a better place in which to hide any number of prisoners than the immense cellars and vaults and dark holes of all sorts, that ran underneath. The building itself was more like a village than a house, and, since its foundation, had been constantly added to and altered, so that it was full of irregularities and steps up and down and roofs at different heights, and passages which once led to something but were now blocked up. On one side of the garden, whose magnificent chestnut trees were the pride of the nuns, stood small houses in which lived noble ladies retired from the world, but free from vows. There was besides a very large vegetable garden for the use of the convent, which at this time contained about a hundred and thirty people. It was possible, if you stood on tiptoe, to snatch a glimpse through the grating of melons or grapes or feathery pinks, but the door was not easy to climb, and only two or three of the bolder girls had ever managed to penetrate into the enclosure and taste these forbidden joys. * * * * * The legend of the concealed prisoner had been handed on from generation to generation of school girls, as well as the terrors which were half a joy, that thrilled through them as they crept along the narrow passages, ending no one knew where--perhaps in the Catacombs, perhaps in the baths of Julian, perhaps outside Paris itself! Who could tell? Could life have any feeling more exciting in store than the sensation that at any moment your feet might meet the empty air, and that you might fall into one of those terrible pits common in castles of the Middle Ages, known by the evil name of _oubliettes_ or holes of forgetfulness? And many of these dangers were not at all imaginary, whatever the 'prisoner' might be. It was the knowledge of the heavy punishments that would fall on their heads in case of discovery that made it a point of honour with the demons to risk everything in order to explore this underground world. Very few, however, gained an entrance to these vaults during their school lives, and only then after years of patience and perseverance. The memory of these heroines was kept green, and their names whispered reverently 'to encourage the rest.' In Aurore's day the question had come up again--the burning question of how to get into the underground world. Not by the main door which led to it, that was clear; for close by were the kitchens, where nuns passed continually! But if the main door was barred, there must be a hundred other doors or walled-up staircases, by which you could get there; and if these failed, there was always the roof.