Elsewhere in Italy paid crimes were probably more or less frequent in proportion to the number of powerful and solvent buyers. Impossible as it is to make any statistical estimate of their amount, yet if only a fraction of the deaths which public report attributed to violence were really murders, the crime must have been terribly frequent. The worst example of all was set by princes and governments, who without the faintest scruple reckoned murder as one of the instruments of their power. And this, without being in the same category with Cæsar Borgia. The Sforzas, the Aragonese monarchs, the Republic of Venice,[1015] and later on, the agents of Charles V. resorted to it whenever it suited their purpose. The imagination of the people at last became so accustomed to facts of this kind, that the death of any powerful man was seldom or never attributed to natural causes.[1016] There were certainly absurd notions current with regard to the effect of various poisons. There may be some truth in the story of that terrible white powder used by the Borgias, which did its work at the end of a definite period (p. 116), and it is possible that it was really a ‘velenum atterminatum’ which the Prince of Salerno handed to the Cardinal of Aragon, with the words: ‘In a few days you will die, because your father, King Ferrante, wished to trample upon us all.’[1017] But the poisoned letter which Caterina Riario sent to Pope Alexander VI.[1018] would hardly have caused his death even if he had read it; and when Alfonso the Great was warned by his physicians not to read in the ‘Livy’ which Cosimo de’ Medici had presented to him, he told them with justice not to talk like fools.[1019] Nor can that poison, with which the secretary of Piccinino wished to anoint the sedan-chair of Pius II.,[1020] have affected any other organ than the imagination. The proportion which mineral and vegetable poisons bore to one another cannot be ascertained precisely. The poison with which the painter Rosso Fiorentino destroyed himself (1541) was evidently a powerful acid,[1021] which it would have been impossible to administer to another person without his knowledge. The secret use of weapons, especially of the dagger, in the service of powerful individuals, was habitual in Milan, Naples, and other cities. Indeed, among the crowds of armed retainers who were necessary for the personal safety of the great, and who lived in idleness, it was natural that outbreaks of this mania for blood should from time to time occur. Many a deed of horror would never have been committed, had not the master known that he needed but to give a sign to one or other of his followers.