The workflow goes from left to right. When new input comes, it goes into your inbox on the left. When it's time to process those items, handle the items in the middle, right in front of you. Any piles that need to be taken somewhere else go on the right side. [...] The system is that you kept your desk clear so that it is available in this way when you are working on things. And so when you are done or at a point where you won't be able to get back to the project for a while, but the reference materials away and the support items back into files, so that the desktop remains clear for whatever is next.