in Act 2 Scene 3 of The Merchant of Venice, explain Launcelot's lines, "Adieu! tears exhibit my tongue. Most beautiful pagan, most sweet Jew! if a Christian do not play the knave and get thee, ................adieu."
Launcelot, who is leaving Shylock's service, is saying goodbye to Shylock's daughter Jessica in this scene. Although he has great animosity towards Shylock, he is very upset at leaving Jessica.
Adieu! tears exhibit my tongue.
Launcelot here is crying openly, and he remarks that his tears are an expression of the sad words of farewell that he is trying to say.
Most beautiful pagan, most sweet Jew!
Launcelot comments on Jessica's appealing qualities, while the same time stressing the fact that she is not a Christian. (Maybe there is an implication, in keeping with the religious bigotry often shown by characters in this play, that Jessica is sweet and loving in spite of being a Jew.)
If a Christian do not play the knave and get thee, I am much deceived.
He says that he will be much mistaken if a Christian does not resort to underhand means and play false to his own religion ('play the knave') in order to win Jessica, a Jew.
But, adieu! these foolish drops do something drown my manly spirit; adieu!
Launcelot cries farewell, while deploring his own 'foolish' tears which weaken and unman him. He does not want to show himself up by crying, but he can't help it.