Related Clues:

• "An __ is salvation by imagination": Frank Lloyd Wright
• Creative output
• Step one of an invention
• Mental inspiration
• Cranial bulb?
• "The very __!"
• Cartoon light bulb
• 'You have no ___'
• Creative inspiration
• Future invention
• What a germ may become
• It starts in your head
• Invention's origin
• Think about it
• Flash of brilliance, perhaps