From Act 3 Scene 2 of The Merchant of Venice by Shakespeare, explain the lines,
"What find I here?
Fair Portia's counterfeit! What demi-god
Hath come so near creation? ................
...............Doth limp being the substance."
This, Bassanio's, speech occurs just after he has chosen the correct lead casket, thus winning Portia's hand in marriage. In the lead casket, he finds Portia's picture ("Portia's counterfeit"): proof that he has chosen correctly. He is amazed at how well the picture has captured Portia's beauty. ("What demigod hath come so near creation?") The picture is so well done that it seems to be alive; Bassanio asks if the eyes in the picture are moving, but then considers that they only seem to be moving because his own eyes are moving. He notes that her lips are parted and concludes that only the sweetest breath could part/"sunder such sweet friends":
Here are severed lips,
Parted with sugar breath. So sweet a bar
Should sunder such sweet friends. (III.ii.121-23)
Continuing to gaze at the picture, Bassanio adds that the painter is like a spider creating a picture like a web. A spider's web is delicate and alluring. So is this picture of Portia. Bassanio wonders how the painter could have continued painting after having painted only one of Portia's beautiful eyes; he thinks that by just painting one of her eyes, he would have been entranced by its beauty and he would be unable to finish the portrait.
Finally, Bassanio says that his high praises of the picture are actually modest ("underprizing") when compared with the praises that he would give Portia herself. The picture is but a "shadow" of the real woman herself. Just as a shadow is only a silhouette that follows a person's profile in the light, the picture is like a shadow that "doth limp behind the substance" - pales in comparison with the actual Portia.