ἔκφρασις or description

ἔκφρασις (ekphrasis) or description is 12th on the list of the ancient progymnasmata.  According to Theon, ekphrasis is,

"descriptive language, bringing what is portrayed clearly before the sight." (Theon 118, Kennedy).

Theon goes on to state that there are ekphrases of persons, events, places, and periods of time.  Virtues of ekphrasis  are clarity and vividness according to Hermogenes (Hermogenes 23, Kennedy).

A good example of ekphrasis from the gospels would be the description of the transfiguration of Jesus.  Take Matthew's account:

Matt. 17:2 καὶ μετεμορφώθη ἔμπροσθεν αὐτῶν, καὶ ἔλαμψεν τὸ πρόσωπον αὐτοῦ ὡς ὁ ἥλιος, τὰ δὲ ἱμάτια αὐτοῦ ἐγένετο λευκὰ ὡς τὸ φῶς.  

And he was transformed before them, and his face shone forth as the sun, and his clothes became white as light."

This description, or ekphrasis by Matthew follows both of Hermogenes' virtues of ekphrasis.  His description is clear and vivid.  To accomplish this vividness, Matthew uses two similes: face shone forth as the sun, and his clothes became white as light.