Related Clues:

• "Ah-ha" predecessor
• Approximation
• Creative germ
• It may come to mind
• What comes to mind
• "What's the big ___?"
• Light bulb, in a cartoon
• Awareness
• Cerebral output
• "Why, the very ___!"
• Invention beginning
• It can be big, bright, good or bad
• Comic lightbulb
• Lightbulb source?
• Birth of a notion