Many artists today make their living by having wacky ideas and pushing them past the limit. I'm fine with that. Phil McGaughy has earned a place in my gallery of Earth art with his notion that "minerals like gypsum, iron and oil may be seducing and exploiting our human ingenuity to achieve their own ends." I wouldn't pay a nickel for the idea itself if I heard it at a partyI might offer geologist Robert Hazen's idea of mineral evolution, also inspired at a party, as a ripostebut I have to be charmed at how McGaughy turned the idea into sculptural forms. What if gypsum, having succeeded in becoming wallboard and plaster, decided to expand its presence onto our office walls?