Bob Boilen of NPR explained:
I supplied some inspiration for their song: photo collages created by artist Tom Chambers. They chose a photograph of a house in a canyon filled with water, tilted and flooded. Not far from the house is a dog on a boat, floating either toward or away from the house. I also supplied a series of words. They selected the word "cerebral" and promised when they wrote the song not to be too cerebral about it. You can hear the music and watch a video documenting the creative process as it unfolds.
Check it out here.