Titus Livius (Livy), The History of Rome, Book 40
Evan T. Sage, Ph.D. and Alfred C. Schlesinger, Ph.D., Ed.

56. When Perseus was informed that everything had been discovered he was indeed too strong to consider that flight was necessary: he arranged only to remain far away, being prepared to defend himself against the flames of burning anger while Philip lived. [2] Philip, although disappointed in the hope of seizing his person for punishment, turned his attention to the course which was still open to him — of seeing to it that Perseus might not, in addition to impunity, also enjoy the profit of his crime. [3] He therefore summoned Antigonus, to whom he was indebted in return for his having exposed the murder, and who, he believed, would be a king about whom the Macedonians need by no means be ashamed or abashed, on account of the recent fame of his uncle Antigonus. [4] “Since I have come to such a state, Antigonus,” he said, “that the bereavement which other parents try to avert cannot but seem to be a blessing, the kingdom which I received from your uncle, held in safe-keeping and even made still greater by his courageous and not merely loyal guardianship, it is in my mind to bequeath to you. I have you alone whom I judge to be worthy of the throne. [5] If I had no one, I should prefer to have it perish and be destroyed to seeing it become for Perseus the reward of his criminal treachery. [6] I shall believe that Demetrius is raised from the dead and restored to me if I shall leave you, who alone have wept at the death of an innocent man and for my unfortunate mistake, as a substitute for him.” After saying this he did not cease to distinguish him [p. 171]with every mark of honour. [7] While Perseus was¹ absent in Thrace, Philip canvassed the cities of Macedonia and recommended Antigonus to the chiefs; and if longer life had been his lot there is no question that he would have left Antigonus in possession of the throne. Setting out from Demetrias, he had been delayed for a very long time at Thessalonica. [8] When he had come from there to Amphipolis he was seized with a severe illness. But it is evident that his sickness was one of the mind rather than of the body; [9] and that anxiety and loss of sleep, while again and again the shade and ghost of the innocent son whom he had killed pursued him, brought about his death while calling down dreadful curses upon his other son.² [10] Nevertheless Antigonus could possibly have been advanced to the throne if he had been present or even if the death of the king had been made public at once. [11] The physician Calligenes, who was in charge of his treatment, without waiting for the death of the king, at the first signs that the case was hopeless sent messengers to Perseus, as he had arranged to do, on relays of horses, and until his arrival concealed the death of the king from all who were outside the palace.