Diodorus Siculus, The Library of History, 16.91-95:

In the archonship of Pythodorus [336 B.C.E.] ... Philip, having been appointed hegemon [commander-in-chief] by the Greek states, commenced the war with Persia by sending ahead into Asia [Minor] an advance expedition under the command of Attalus and Parmenio, with orders to liberate the Greek city-states there. Philip himself, anxious to have divine approval, consulted the Pythia [priestess at Delphi] to ask if he would defeat the Persian king. She responded as follows: "The bull is garlanded [for sacrifice]. All is ready and the sacrificer is at hand."

Though the response was equivocal, Philip took it as propitious to himself: that is, predicting the death of the Persian king. In fact, it foretold Philip's own death at a festival with solemn sacrifices; he, like the bull, would die wearing religious wreaths. But Philip rejoiced to think that he had the backing of the gods and trusted that Macedonian arms would subjugate Asia [Minor].

Philip now made plans for spectacular celebrations for the gods, in conjunction with the wedding of his and Olympias's daughter, Cleopatra, who was marrying Alexander, the king of Epirus (and brother of Olympias). Eager to have as many Greeks as possible participating in the sacred observances, he scheduled elaborate musical displays and feasts for his guests. He invited his own friends from all over Greece and urged his courtiers to do the same. He intended to impress the Greeks with his civility and to repay the honors bestowed on him as supreme commander by staging an appropriate social event.

Many people came to the festival at Aegae in Macedonia from all parts both for the games and for the marriage. Philip was awarded golden crowns not only by individuals but also by many major city-states, including Athens. When the herald announced the Athenian decoration, he closed by saying that the Athenians would surrender anyone plotting against Philip and seeking refuge at Athens. The words (later) seemed an omen from the gods that a conspiracy was in fact approaching. There were several other sayings at the time that seemed to foreshadow the king's demise....

The games were to begin the next day. The theater was already packed before dawn, and at sunrise the lavish procession began: it included dazzling images of the twelve Olympian gods meant to awe the spectators; and to the twelve was joined a thirteenth--that of Philip himself.

Philip appeared at the crowded theater attired in a white mantle. He bid his bodyguards to keep their distance, meaning to demonstrate his confidence in the adulation of the Greeks, which made armed guards unnecessary. Amidst the general applause and raves, the plot to assassinate unfolded itself. In the interest of clarity, I will examine the motives for it.

A Macedonian, Pausanias by name, from the Orestis district, had been a member of the king's bodyguard. Because of his attractiveness, Philip became his lover. When Philip then turned his attentions elsewhere (to another man named Pausanias), the first Pausanias mocked the second by saying he was androgynous and promiscuous. Cut to the quick by this slur, the second Pausanias secured his own death in a sensational way, after confiding in Attalus what he was intending to do. For, some days later, during a battle with Pleurias, an Illyrian king, Pausanias shielded Philip's body with his own, and died from fatal wounds so received.

The incident was widely reported. Attalus, a man of standing and influence in the court of Philip, thereupon invited the first Pausanias to dinner. Having gotten him drunk on undiluted wine, he then handed him over nearly unconscious to be raped by his mule-drivers. Pausanias, once sobered up, was deeply aggrieved by the assault on his person and denounced Attalus to the king. Philip, however, although outraged at the brutality of the deed, did not choose to bring Attalus to account because of their affiliation and because he had need of the man's services at the moment: Attalus was the [uncle] of Philip's new wife, Cleopatra, and, owing to his valor, had just been appointed general of the forward forces in Asia. Thus, Philip instead tried to quell Pausanias's justifiable rage over his injury by giving him gifts and elevating his position in the corps of his personal bodyguards.

Pausanias for his part kept his grudge and longed to exact vengeance not only from the man who had injured him, but also from the one who had declined to redress the injustice. His teacher, the sophist Hermocrates, unwittingly inspired him in his scheme. When Pausanias asked him how one could become most renowned, the sophist answered: "by slaying the man whose achievements were the greatest, for the assassin's fame would endure as long as the great man's." Pausanias took this opinion as applicable to his own situation. He immediately resolved to revenge himself during the distractions of the wedding festival. Having readied horses at the city gates, he went to the entrance of the theater carrying a concealed Celtic dagger. Philip on his arrival bid his companions to enter ahead of him and, with his bodyguard ordered to keep their distance, was by himself. Pausanias darted forward and stabbed the king through his ribs, killing him instantly. He then made a dash for the gates and his getaway horses. Meantime, the royal bodyguards sprang into action, some rushing to the fallen king, others pursuing the killer; these included Leonnatus, Perdiccas, and Attalus [not the uncle of Cleopatra]. Pausanias nearly made it to the waiting horses, but his shoe caught in a vine and he fell. As he was getting up, Perdiccas and the others overtook him and slew him with their javelins.

So perished Philip, the greatest European monarch of his era. The vast extent of his rule led him to claim a throne among the twelve great Olympian deities. He reigned twenty-four years, in that time rising from a man with little support for his claim to the throne to ruler of the greatest empire in Greece. The success of his career derived not so much from his military genius as from his facility and tact in diplomacy. They say that he prided himself more on his skills of strategy and diplomacy than on his battlefield courage, for his whole army shared the credit for success in combat, while he alone got the recognition for diplomatic victories.