Make a virtue of necessity
I'm the Second Outlaw. I steal and live outside the law to make my way. I am an outlaw, after all. And you know what I think?
Indeed, because you are a banish'd man,
Therefore, above the rest, we parley to you:
Are you content to be our general?
To make a virtue of necessity
And live, as we do, in this wilderness? (4.1.59-63)
Who Said It and Where
"Will you be my valentine?"
That's what our boy Valentine asks when he meets and falls in love with the beautiful and sassy Silvia. The catch? Silvia treats Valentine like her "servant" and he loves every minute of it. That's how guys and girls flirt in "courtly romance" literature, which Shakespeare is, to some extent, making fun of here.
But there's trouble in paradise, because when Proteus (a.k.a. the other gent of Verona) shows up, he promptly falls in love with Silvia, forgetting all about the girl he left back home. Then Proteus does something awful—he tattles on Valentine (who plans to elope with Silvia) to Silvia's protective father, the Duke of Milan. That's below the belt, bro.
When the Duke approaches Valentine, a steamy lover letter to Silvia and a rope ladder fall out of the young man's jacket. (We're not sure how all that stuff fit in his coat, but we're willing to suspend our disbelief.) The Duke says something like "A-ha! You're planning to climb that ladder up to my daughter's bedroom. Get out of my sight." Ultimately, the Duke banishes Valentine from Milan. If Valentine shows his face in town ever again, he'll be put to death.
Naturally, Valentine flees to the forest between Milan and Mantua with his buddy Speed, and they run into a group of outlaws. One of the outlaws says "stick em' up" and Valentine proceeds to explain that he's got nothing for the roadside robbers to steal. Dude's flat broke and busted.
The outlaws are impressed when they hear that Valentine has been banished from Milan. They're even more impressed when Valentine lies about having "killed a man." See, now they think of Valentine as some kind of Robin Hood figure and invite him to join their bad boy club. Then they all take turns bragging about their crimes. Valentine agrees to join the outlaw club but makes them promise not to hurt any women or defenseless travelers. They agree and set off to live as a band of happy bachelors.