From Act 3 Scene 2, from the extract, " Look on beauty, And you shall see 'tis purchased by weight; Which therein works a miracle in nature, ..........to a most dangerous sea.'
1. Explain how is beauty purchased by weight and does it makes the wearers lightest?
In this section of Act 3, Scene 2, one of Bassanio's themes as he considers which casket to open is the mis-leading nature of things, that is, objects and people who may look wonderful and powerful are, when you look within, worthless.
In this passage, Bassanio focuses not on people who seem to be brave and strong, and who turn out to be cowards, but on women who look outwardly beautiful:
Look on beauty,/And you shall see 'tis purchased by the weight;/Which therein works a miracle in nature,/Making them the lightest that wear most of it: (3:2:88-91)
Bassanio is essentially saying: "Let's look at another example--beauty. You shall see that it is created with pounds of cosmetics, which work miracles, making the women who wear the most cosmetics the most frivolous (or the most wanton or licentious). In Shakespeare's time, the word lightest could refer to sexual looseness or just frivolousness (that is, not serious). How we translate lightest, choosing either most wanton or most frivolous, is not as important as understanding that Bassanio is continuing to provide examples of beautiful items, like the casket, whose beauty or value is only external.