"You have told me," he said, "that your people, with whom you lived in that secluded valley high up in the Andes, had with them the 'karina' and cultivated it. Therefore I suppose you yourself have been in the habit of taking it?" "Always. And in my travelling to and fro in the world I always had with me a good supply of the dried herb. I was accustomed to leave stores of it in certain towns, so that if I lost what I had with me by any accident, there was more within easy reach." "I see. But what I am puzzled about is this: why, if the virtues of the plant are so great, do people ever die at all? And why do some live longer than others?" "As to the first question," Monella answered, "man was never intended to live on this earth for ever. The human frame _must_ wear out sooner or later. As to the second query, some constitutions are naturally stronger than others, and these endure longer, just as is the case in the world outside where the plant is not known. The effect of the plant is simply to keep the blood pure, if originally pure. If, however, there is an inherited taint, that taint will make itself felt sooner or later and undermine the vitality of the system. In this case the plant will only result in ensuring a somewhat longer life than would otherwise have been the case. Sooner or later the vitality will fall off and gradual decay set in, although (the blood being kept still pure) ordinary diseases are kept at bay. Lastly, there is the question of the will." "The _will_?" "Yes; that has a most powerful influence. If a man who has inherited a constitution that is absolutely sound, from ancestors who have possessed the same through many generations, and if he has, in addition, a strong _will_, powerful beyond the average, he may live longer--if he is so minded." "I--do not understand you," said Templemore, somewhat puzzled. Monella gazed at him with a smile that was full of sadness.