In Act 4, Scene 1, the friar uses ethos to persuade Leonato of Hero's innocence despite the allegations against her. He says:
Call me a fool,
Trust not my reading nor my observations,
Which with experimental seal doth warrant
The tenor of my book; trust not my age,
My reverence, calling, nor divinity,
If this sweet lady lie not guiltless here
Under some biting error.
By telling Leonato not to trust his learnedness, observations, age, or social status, the friar conversely emphasizes his level of authority. In doing so, the friar successfully persuades Leonato to believe what he has noted based on his observations: namely, that Hero is innocent. Although the allegations that Hero has been unfaithful are similarly based on what others have noted, the friar's respected position in society as a man of the church grants his perceptions more authority than any one else's opinions or judgments. Although the play is filled with characters who distort the truth through rumors and disguises, the friar's use of ethos suggests that earnest and informed observation does have the capacity to provide access to the truth.