From Act 3 Scene 2, from the extract " there is no vice so simple but assumes Some mark of virtue on his outward parts: ...........to render them redoubted!
How can vice assume the external show of virtue?
Perhaps the greatest feature of Shakespeare's plays is the eloquent language. In this particular scene of Act III, there is much beauty of language, to be sure, and it enhances the meaning of Bassanio's deliberation over the caskets. In fact, his reflection about the blurring of vice and virtue is suggested in another of Shakespeare's plays, Romeo and Juliet, in which Friar Laurence soliloquizes in Act II, Scene 3 that taken to a certain point, there is a thin line between virtue and vice.
Virtue itself turns vice, being misapplied,And vice sometime by action dignified. (2.3.21-22)
There is no vice so simple but assumes
Some mark of virtue on its outward parts. (3.2.81-82)
Thus ornament is but the guiled shore
To a most dangerous sea, the beauteous scarf
...in a word
The seeming truth which cunning times put on
To entrap the wisest. (3.2.97-101)