Related Clues:
- Start of a project
- Mental concept
- Project's basis
- It might just come to you
- In the end, Russell returns to papers with proposal
- Think tank's quest
- It might pop into your head
- Skull session result
- Coconut product?
- Black cloud : anger :: light bulb : __
- Brainy creation
- Inventor's brilliant notion
- Bit of brainwork
- Mental spark
- Light in the attic?