In Othello, the handkerchief is an important part of the story. Othello demands that Iago give him "ocular proof" of Desdemona's unfaithfulness. The cherished handkerchief becomes the proof that Othello needs to accuse his wife of having an affair with Cassio. The handkerchief is the evidence that Othello needs to be convinced that his wife is guilty of infidelity.
The handkerchief is the item that convinces Othello of his wife's unfaithfulness. He gave her the handkerchief with the story behind it. Othello's mother gave him the handkerchief. The story behind it is this:
Gave that handkerchief to my mother;
She cast charms and could almost read
The thoughts of people. She told her, that, while she kept
It, it would make her sweet and soften my father
Entirely to her love; but if she lost it
Or made a gift of it, my father's eye
Should see her as hateful, and his spirits should hunt
After new loves. My mother, dying, gave it to me,
And asked me, when my fate would have me marry,
To give it to my wife. I did so. And take heed about it.
Make it as darling as your precious eye.
To lose it or give it away is such complete destruction
That nothing else could match it.
For Othello, the handkerchief represents fidelity. He is convinced that there is a charm placed on the handkerchief. It symbolizes faithfulness in marriage. For Desdemona to part with the handkerchief is to say she has parted with her vows of faithfulness. The handkerchief is Othello's proof that Desdemona has been careless in their marriage. Othello believes that Desdemona has been unfaithful. He is convinced because Cassio holds the handkerchief that is a symbol of Othello's love and faithfulness to Desdemona.