Related Clues:

• Inventor's ''step one''
• Bright one from gray matter
• Inventor's start
• Light bulb's signification, in cartoons
• Light bulb, in comics
• Topic
• Mental glimmer
• Object of thought
• Head piece?
• Bacon bit?
• Creator's sine qua non
• Emerson piece
• Brainchild
• Theory
• Take a crack at