MESSENGER Much deserved on his part, and equally remembered by Don Pedro. He hath borne himself beyond the promise of his age, doing in the figure of a lamb the feats of a lion. He hath indeed better bettered expectation than you must expect of me to tell you how. (1.1.12-17)
Claudio isn’t just praised for being a great soldier: it’s of particular importance that one so young has proven himself on the battlefield. This qualification will be important throughout the play. Though Claudio will have adult feelings (especially about love), he’s still young. While he has experience in battle, he has no such experience yet with love, which sheds light on his immature behavior towards Hero.
DON PEDRO Well, as time shall try. In time the savage bull doth bear the yoke. (1.1.255-256)
Don Pedro’s been around the block, and he’s mature enough to realize that even the savage bull can be tamed. He knows men can change their minds, which is, interestingly, exactly the conclusion Benedick comes to in the very end of the play... after he’s had some time to mature himself.
CLAUDIO How sweetly you do minister to love, That know love's grief by his complexion! But lest my liking might too sudden seem, I would have salved it with a longer treatise. (1.1.307-310)
Even Claudio recognizes that seeming to fall in love quickly is a mark of immaturity.
Act II, Scene i
DON PEDRO I will but teach them to sing and restore them to the owner. (2.1.229-230)
Don Pedro is mature enough not to be caught in the drama of deception. Realizing Benedick and Claudio think that he’s stolen away Hero’s affection, he rights the whole situation by simply pointing out that he hasn’t done anything wrong—he will give Hero to Claudio as promised. Thus we learn disaster can be averted by simply being mature and up front.
LEONATO Well then, go you into hell? BEATRICE No, but to the gate, and there will the devil meet me like an old cuckold with horns on his head, and say 'Get you to heaven, Beatrice, get you to heaven; here's no place for you maids.' So deliver I up my apes, and away to Saint Peter; for the heavens, he shows me where the bachelors sit, and there live we as merry as the day is long. (2.1.42-49)
Beatrice seems comfortable with her choice to live an old maid, to the point where she’s even able to joke about the possibility of going to hell (which was assumed to be the final destination for unmarried women). She’s certain there’s nothing actually wrong with her, that she’s earned her place in heaven, and further, she’s happy to be single. This attitude—not of fury, or self-pity—is a pretty mature one, even if it’s a little bit of a front.
Act II, Scene iii
BENEDICK [aside] I should think this a gull but that the white-bearded fellow speaks it. Knavery cannot, sure, hide himself in such reverence. (2.3.126-128)
Benedick trusts that Leonato, as an old and respected man, wouldn’t be in on this conversation if it were a trick. Respect comes with age... though maybe age shouldn’t always be trusted.
Act V, Scene i
CLAUDIO We had like to have had our two noses snapped off with two old men without teeth. (5.1.128-129)
To Leonato’s face, Claudio makes a big show of respecting his age, but it’s clear from this comment that Claudio is not exactly Mr. Reverence. Age doesn’t seem to command respect for Claudio; he approaches it more as a weakness than a reason for reverence, which is pretty immature of him. It’s another strike against Claudio’s character.
LEONATO Tush, tush, man, never fleer and jest at me. I speak not like a dotard nor a fool, As under privilege of age to brag What I have done being young, or what would do Were I not old. Know, Claudio, to thy head, Thou hast so wrong'd mine innocent child and me That I am forced to lay my reverence by, And with grey hairs and bruise of many days Do challenge thee to trial of a man. (5.1.65-73)
Leonato lays out the two sides of aging: On one hand, age demands respect, but on the other hand, old age also makes people weaker, which lets young punks abuse them.
Act V, Scene iv
BENEDICK In brief, since I do purpose to marry, I will think nothing to any purpose that the world can say against it, and therefore never flout at me for what I have said against it. For man is a giddy thing, and this is my conclusion. (5.4.108-113)
Benedick exhibits real maturity in his thinking. Here, he admits that he might seem like a hypocrite, but has decided that his love is more important than his ideological consistency.