When the seed of jealousy is sown in his mind, it begins to grow like moss in the sea. The work revolves around four central characters: Othello, Othello's wife Desdemona, his lieutenant Cassio and advisor Iago.
He shows this theme throughout the book by giving Othello, the main character, the trait of low self-confidence. To "prove" something is to investigate it to the point where its true nature is revealed. Once Iago inflames Othello's jealousy and sets the darker aspects of Othello's nature in motion, there is nothing Othello can do to stop it, since he cannot even admit that he has these darker traits.
The entire play of Othello conveys a motion that of a Shakespearean Tragedy. He is tough, determined and committed to justice and righteousness.
But he is also victimized by an unjustified, but terrible hatred. When Shakespeare wrote Othello, viewing the play was an event in itself, not an hour and a half thrill ride that today's viewer have come to expect.
Indeed, it is jealousy that provides the fuel for the plot and deception that leads to the classic downfall of the 'hero' as is common in Shakespeare tragedies.