"Insights and perceptions pass through the mind like fleet fireflies. Lit for an instant, then gone back into the dark. They are precious, irreplaceable. Stop what you are writing and write them into a notebook, onto a napkin, a scrap of paper. ANYWHERE. They are more important than what you are writing now. What you are writing now is there. It is visible, tangible. You will not lose the mood, the flow, the roll."
From "Dare to be a Great Writer: 329 Keys to Powerful Fiction"