[hyperpallium]

> [paraphrasing] get some good idea along the way devote a minute to write down a “stub” for that (just enough to jog your memory when you return), so as not to break your concentration or momentum

This "stub" or aide-mémoire doesn't define the idea, just evokes it. So you better come back while that memory is still fresh, or you will not be able to work out what it was!