Why does Caesar not read Artemidorus's letter in III.1 of Julius Caesar?
Caesar marches on Rome after defeating his rival. His arrival is received with much pomp and fanfare. A triumph is organized for him, and the citizens merrily attend the function. However, a section of the elite is not happy with how Caesar is positioning himself. During the triumph, Caesar is offered a crown by Marc Antony, which he rejects, gesturing that he would rather cut his throat. His actions endear him to the common citizen, but the elite read mischief. The Soothsayer warns Caesar to beware the Ides of March, which signify the plot to kill him. Artemidorus also reads a paper that warns Caesar to beware of Brutus, Cassius, Casca, Cinna, Trebonius, Metellus Cimber, Decius Brutus and Caius Ligarius. Upon the discovery, Artemidorus seeks to inform Caesar of the plot, but when he presents his suit before Caesar, Caesar refuses to read it. He states that matters touching on him personally will be read last. His response is an attempt to demonstrate his selfless nature and his populist agenda.
You could say that the Fates decreed that he not read the letter because his fate had already been determined. In the play, however, it is the way Artimedorus presents the message that makes Caesar turn him away. As Caesar arrives at the capitol, both Decius and Artimedorus approach him with petitions. Artimedorus shouts that Caesar should read his petition right that minute because it is a message that "touches Caesar nearer." However, Decius presents his message by saying that Caesar can read his "humble suit" at Caesar's "best leisure." In a move meant to show his own humility, Caesar says that any message that concerns his own good should be the last thing he considers. So he brushes Artimedorus aside.
Caesar does not read the letter out of arrogance. He says that Artemidorous must be mad to stand in his way. He also ignores the warnings of the Soothsayer. Because Caesar continues on his way to the Senate, he becomes easy prey for the Conspirators, and he meets his death.