The Garden of Earthly Delights, by Hieronymus Bosch (c.1500, Prado Museum, Madrid).
That’s the painting featured in Person of Interest, Season 3, Episode 20 (Death Benefit). In the episode Senator Garrison (John Doman) meets John Greer (John Nolan) in the art museum just in front of the triptych.
As for the meaning, some critics have interpreted the triptych as warning on the transience of earthly pleasure. Proponents of this idea though pointed out that the triptych’s center panel portrays a joyous world - when humanity will experience a rebirth of the innocence enjoyed by Adam and Eve before their fall. Or that it represents the state of mankind on the eve of the Flood.
In recent years several art historians have emphasized the ironic elements of ’’The Garden”. According to their interpretation “Bosch does not present a clear, but an ambiguous world. […] It can be understood as a moral insight into the incurability of human folly, whose ridiculousness only becomes endurable by laughing.”