"Such, my friends, were the masterpieces of the Borgia, for whom the profoundest chemists worked willingly enough and by doing so doubtless made their fortunes. Their poisons were so designed to act that, by their very operation, the secrets of them were concealed, and all clues obliterated. Chemistry knows nothing of the supernatural, yet can, as in this case, achieve results that may well appear to be black magic. "And if we, of this day, fail to find them out, it is easy to guess that in their own times, much that they caused to be done was set down to the operations of Heaven alone. "Science will be deeply interested in your Borgia mattress, Sir Walter. Science, I doubt not, will carefully unpick it and make a series of very remarkable experiments; yet I make bold to believe that science may be baffled by the cunning and forgotten knowledge of men long dust. We shall see as to that." He rose and bade Masters call Stephano. Then, with a few words, they parted, and each shook the old man's hand and expressed a deep and genuine gratitude before they did so. "A little remains to add," said Signor Mannetti. "You shall hear what it is to-morrow. For the moment, 'Good-night!' It has been a crowning joy to my long life that I was able to do this service to new and valued friends." In the servants' hall next morning Masters related what he had heard. "And if you ask me," he concluded, "I draw back what I thought about him being younger than he pretends. He's older--old as the hills--older than that horror in the Grey Boom. He's a demon; and he's killed the old dog; and I believe he's a Borge himself if the truth was known." CHAPTER XIII. TWO NOTES They walked in the garden next morning, and Sir Walter delayed to write to Scotland Yard until after seeing Signor Mannetti again. The old gentleman descended to them presently, and declared himself over-fatigued. "I must sit in the sun and go to sleep again after lunch," he said. "Stephano is annoyed with me, and hints at the doctor." "Mannering will be here to lunch. You will understand that nobody is more deeply interested in these things than he." "But yourself," said Mary. "Come and sit down and rest. You are looking very tired to-day." "A little reaction--no more. It was worth it." He then proceeded where he had broken off on the preceding night. "There remains only to tell you how I found myself caught up in your sad story. It had not occurred to you to wonder?" "I confess I had never thought of that, signor. You made us forget such a trifling detail."