The soliloquy begins with Iago expressing his hatred for Othello. He calls Othello "the Moor" and "the thick-lips," and he refers to him as "an old black ram" who has "tupped" Desdemona, a white woman. Iago's hatred is based on several factors, including his belief that Othello is inferior to him because of his race, his jealousy of Othello's success with women, and his desire for power.
Iago then goes on to describe his plans for revenge. He says that he will "poison Othello's ear" with lies and make him believe that Desdemona is unfaithful. He will also use Cassio, Othello's lieutenant, to help him carry out his plans.
The soliloquy ends with Iago expressing his confidence that he will be successful in his revenge. He says that he is "the motive spirit" of the plot and that he will "make Othello mad" and "destroy him."
Iago's soliloquy is a chilling and powerful speech. It reveals the depths of his evil and his determination to destroy Othello. The soliloquy also sets the stage for the tragic events that will follow.