In the first act the reader see the use of rhetorical-linguistic instruments aimed to emphasize the debut of the plot concocted by Iago at the expense of Othello. Among them, in the dialogue between Iago and Roderigo, is particularly insistent the use of the imperative, attestation of the persuasion that Iago adopts towards the other character. He wants to convince Roderigo that he was the one who deserved the role of lieutenant. He makes use of direct speech, reporting Othello’s words and shaping the characterization of Cassio, describing it negatively by accumulation and above all, using irony. This rhetorical instrument will be adopted by Iago in the course of all his dialogues; I report some examples: "A fellow almost damn'd in a fair wife"; "[...] Nor the devision of a battle knows More than a spinster"; "Mere prattle, without practice", etc.

The irony reveals Iago’s contempt and envy towards Cassio and, all the wile, it shows feelings such as frustration, resentment and hatred, at the base of his lust for revenge.

You can also deduct his considerable oratorical skills and ability in simulation and dissimulation. He in fact declares conflicting sentences, which vary depending on the context and on the interlocutor. For example, on the one hand, he urges Roderigo to rail against the Moro ("Rouse him, make after him, poison His delight, incense her kinsmen, and, though he in a fertile climate dwell, plague him with flies."), From 'another, in the dialogue with Othello himself, he pretends to act to protect the health, safety and welfare of his lord. He provides him with recommendations and he addresses him as "captain". Speaking with Roderigo, he partially declares his intent , he provides information that suggest that he is planning something, acting on its own particular purpose. ("Not I for love and duty, but seeming so, for my peculiar end").  He suggests to the reader a possible course of the plot, favoring the suspense. Thus, there are words and expressions related to the semantic field of the mystery, of disguise and hiding, such as: "" trimm'd in forms and visages of duty "; "Throwing but shows ..."; "Seeming"; "Demonstrate; "The native act"; "I am not what I am."