I had long ago discovered that when a word or formula refused to come to mind the best thing for it was to think of something else: tigers for instance or oatmeal. Then when the fugitive word was least expecting it I would suddenly turn the full blaze of my attention back onto it catching the culprit in the beam of my mental torch before it could sneak off again into the darkness.
Alan BradleyWhenever I'm out-of-doors and find myself wanting to have a first-rate think, I fling myself down on my back, throw my arms and legs out so that I look like an asterisk, and gaze at the sky.
Alan Bradley