In Act 2 Scene 3, What early indications does the audience have that Othello has the capacity to surrender to his passion or emotions? Any quotations that can show this as well?

Now, by heaven,

My blood begins my safer guides to rule,

And passion, having my best judgment collied,

Assays to lead the way. If I once stir,

When Othello hears of the fight involving Cassio, he is already beginning to lose his cool. This is exactly what Iago expects him to do. While his mind is clouded with anger, Iago will manipulate his mind.