"When suddenly an idea comes to mind, do not wait for her to go away ... Write her down somewhere."
That is a precious advice!
If we do not record an idea that comes to mind, it usually goes away because the circumstances in which the individual lives are changing. The philosopher Heraclitus said that one should never bathe twice in a river. It seems that the process or the itinerary of our thoughts escapes us. Sometimes we want to get rid of an idea but it resists the forgetfulness, other times we want to remember an idea but we do not manage to get it out of oblivion. So given our limited ability to govern our ideas, we must record whatever comes to mind. The only remaining obstacle is: whether the conditions in which the idea came to mind, allow us to register it or not?