Please explain Bassanio's speech in Act III, scene 2 of The Merchant of Venice.
How many cowards whose hearts are all as false as stairs of sand wear yet upon their chins the beards of Hercules and frowning Mars?
Here is more of the speech you're asking about:
There is no vice so simple but assumes
Some mark of virtue on his outward parts.
How many cowards, whose hearts are all as false
As stairs of sand, wear yet upon their chins
The beards of Hercules and frowning Mars;
Who, inward search'd, have livers white as milk;
In this scene, Bassanio has to choose from among the three caskets, or chests, the one that will grant permission to marry Portia. In this speech, Bassanio is talking to himself about how to make his choice. The gist of the speech is that appearances can be deceiving. There is one gold box, one silver box, and one lead box. Just like the cowards who put on the appearance of being brave by dressing and acting like Hercules or Mars, the boxes made of precious metals might contain nothing. So he reasons that what he wants is in the box made of lead, and he is right.