When Othello recalls seeing Cassio with Desdemona’s handkerchief, he uses a simile that links the idea of memory with infection:
O, it comes o’er my memory
As doth the raven o’er the infectious house,
Boding to all - he had my handkerchief.
Othello’s comparison of the memory to the “raven o’er the infectious house” alludes to contemporary folklore of ravens hovering above houses visited by the plague. Such a reference was contextually very important, with the plague being a major part of life for Shakespeare and his audience. Indeed, it is speculated that Shakespeare’s own son Hamnet died of the plague in 1596, and in 1603, when Shakespeare was writing Othello, there was a severe outbreak of the plague in England. For Shakespeare and his audience, therefore, the plague and infection served as powerful and pertinent symbols of danger and tragedy. The choice to compare Othello’s memory with infection thus immediately signals danger and sorrow for the audience.
The comparison of memory with infection also conveys the idea of the brain’s susceptibility to a kind of figurative infection, a theme which becomes paramount in Iago’s poisoning of Othello’s thoughts. Indeed, it is in this very scene that Othello’s mind becomes fully infected by the narrative that Iago is spinning of Desdemona’s infidelity. The link of memory to illness also associates the mind with frailty, a connection which emphasizes the mind’s vulnerability to manipulation and deceit.