A Portrait To Reinforce Your Views

Blake Gopnik defines what makes one great:

Mona Lisa herself has been variously described as straightforwardly cheerful (in her own era), as brimming with femme-fatale lust (in the vixen-obsessed 19th century), and as cryptic and opaque (the 20th-century view). … What a great portrait really needs to do is act as a vehicle for what people already know about someone.