he moved a little on purpose and muttered something aloud that he might not have the appearance of hiding , then rang a third time , but quietly , soberly , and without impatience , recalling it afterwards , that moment stood out in his mind vividly , distinctly , for ever ; he could not make out how he had had such cunning , for his mind was as it were clouded at moments and he was almost unconscious of his body an instant later he heard a series of quick footsteps cascading downwards off the fifth floor .