The answer of Marcus is noble and characteristic: "I have read your letter, and I will confess to you I think it more scrupulously timid than becomes an emperor, and timid in a way unsuited to the spirit of our times. Consider this--if the empire is destined to Cassius by the decrees of Providence, in that case it will not be in our power to put him to death, however much we may desire to do so. You know your great-grandfather's saying,--No prince ever killed his own heir--no man, that is, ever yet prevailed against one whom Providence had marked out as his successor. On the other hand, if Providence opposes him, then, without any cruelty on our part, he will spontaneously fall into some snare spread for him by destiny. Besides, we cannot treat a man as under impeachment whom nobody impeaches, and whom, by your own confession, the soldiers love. Then again, in cases of high treason, even those criminals who are convicted upon the clearest evidence, yet, as friendless and deserted persons contending against the powerful, and matched against those who are armed with the whole authority of the State, seem to suffer some wrong. You remember what your grandfather said--Wretched, indeed, is the fate of princes, who then first obtain credit in any charges of conspiracy which they allege--when they happen to seal the validity of their charges against the plotters, by falling martyrs to the plot. Domitian it was, in fact, who first uttered this truth; but I choose rather to place it under the authority of Hadrian, because the sayings of tyrants, even when they are true and happy, carry less weight with them than naturally they ought. For Cassius, then, let him keep his present temper and inclinations; and the more so--being (as he is) a good General--austere in his discipline, brave, and one whom the State cannot afford to lose. For as to what you insinuate--that I ought to provide for my children's interests, by putting this man judicially out of the way, very frankly I say to you--Perish my children, if Avidius shall deserve more attachment than they, and if it shall prove salutary to the State that Cassius should live rather than the children of Marcus."