Leonato is the governor of Messina, where this excellent comedy is set, and is the father of Hero. He is involved in the gulling of Benedick and Beatrice and shows great wit and humour in his speech. However, perhaps most interestingly, we see a very different type of figure emerge at the wedding when Claudio denounces Hero as a whore. Notice how, after he has received verification from Don Pedro, Leonato turns on his daughter and clearly states that he wishes she were dead:

O she is fallen

Into a pit of ink, that the wide sea

hath drops too few to wash her clean again,

And salt too little which may season give

To her foul, tainted flesh.

However, we do see a repentant Leonato who recognises that his daughter has been much maligned and therefore challenges Claudio to a duel. Leonato is relentless in discovering the truth of how Don John managed to trick so many and then is determined that Claudio will apologise suitably for the damage he has done. So, although his speech is marked in its anger, we would do wrong to judge him based solely on this speech. He, after all, is just one of many very wise characters who was duped by Don John's treachery.