How is The Canterbury Tales a picture gallery?
The "Prologue" of Geoffrey Chaucer's The Canterbury Tales gives readers a distinct picture of the characters (or pilgrims) on their way to visit the shrine of Thomas Becket. Challenged by the owner of the inn, the pilgrims must tell a tale of morality. Ironically, each tale told highlights the teller's own vices and fallacies.
As for The Canterbury Tales acting as a picture gallery, the "Prologue" introduces each of the pilgrims describing them using both physical and internal traits.
For example, the "picture" of the Monk details a man with big, sparkly eyeballs. He is both bald and fat. Unlike what would be expected of a monk, the Monk wears fine fur-trimmed clothing and expensive riding boots. His face is both tanned and greasy.
His head was bald and shone like any glass
And smooth as one anointed was his face.(35)
Fat was this lord, he stood in goodly case.
His bulging eyes he rolled about, and hot
They gleamed, and red, like fire beneath a pot.
Each character in Chaucer's tale is depicted in the same fashion. While some are described using more detail, all of the characters are described using such detail that one could create a mental picture book of each.