thought it was L&L but not sure
"Many of the things built by the architect and freelance designer Bergholt Stuttley ('Bloody Stupid') Johnson were recorded in Ankh-Morpork, often on the line where it says 'Cause of Death'. He was, people agreed, a genius, at least if you defined the word broadly. Certainly no one else in the world could make an explosive mixture out of common sand and water. A good designer, he always said, should be capable of anything. And, indeed he was."
What would good do if evil didn't exist, and what would the earth look like if all the shadows disappeared?