Titus Livius (Livy), The History of Rome, Book 40
William A. McDevitte, Sen. Class. Mod. Ex. Schol. A.B.T.C.D., Ed.

5. The barbarity connected with this deed added fresh fuel to the flame of public resentment kindled against the king, insomuch that most people uttered imprecations on himself and his children; which curses being in a short time heard by all the gods, caused him to vent his cruelty on his own blood relations. [2] For Perseus, when he perceived that the popularity and high reputation of his brother Demetrius among the Macedonian people, and interest among the Romans, increased more and more every day, and that no hope was left him of obtaining the crown save by the instrumentality of some wicked device, bent all his thoughts to that one object. [3] But not thinking himself alone strong enough even for the dastardly project, which he meditated in his effeminate mind, he began to tamper with each of his father's friends by dark suggestions. [4] At first, several of these showed an appearance of rejecting with scorn any such overtures, because they entertained higher expectations from Demetrius. Afterwards Philip's animosity to the Romans increased every day, which Perseus fomented; but Demetrius, with all his might, opposed. [5] Foreseeing the fatal doom of the youth, who heeded not a brother's guile, and thinking that they must lend their assistance to the accomplishment of what was likely to take place, and cherish the hopes of the more powerful, they united themselves to Perseus. [6] They defer the execution of other measures till their proper season; for the present, it seems good that the king should by every strenuous exertion be inflamed against the Romans, and urged to form resolutions for war, to which he had already of his own accord turned his attention. [7] At the same time, in order that Demetrius might be a greater object of suspicion every day, they used deliberately to prolong the conversations even to the use of insulting language towards the Romans; thereupon, when some depreciating their manners and institutions, some their military achievements, some the appearance of the city itself, unadorned [p. 1859]either by public or private structures; others spoke scornfully of some particular individuals among their principal men. [8] On these occasions, the young prince unwary, both out of affection for the Roman nation, and opposition to his brother, by maintaining their cause in all things, rendered himself an object of suspicion to his father, and a fit subject for their accusations. [9] His father therefore kept him a stranger to all his designs respecting the Romans; he was entirely devoted to Perseus, and held with him, daily and nightly, deliberations on that subject. [10] The envoys had returned whom he happened to have sent to the Bastarnians, to solicit aid, and brought with them from thence young men of distinction, and some of royal extraction; one of whom promised his sister in marriage to Philip's son, and the connexion with that nation raised the king's spirits. Hereupon Perseus said, “What does that avail? [11] There is by no means as much protection afforded by foreign aid, as there is danger arising from domestic treachery. [12] I am unwilling to call him traitor, but a spy we certainly have in our bosom, and although the Romans have restored to us his body, since he was a hostage at Rome, yet they still possess his heart. The faces of almost all the Macedonians are turned towards him, and they think they are to have no other king but him whom the Romans would give them.” [13] By such discourses the old man's mind, distempered in itself, was stimulated to passion, and these imputations he [14??] received deeper in his mind, than appeared from his countenance.