Other pupils reading Psychology and Philosophy interpreted it differently. Blue, they said, was right for going into an examination, because one felt blue about it: red was appropriate for the past, which one viewed through rose-tinted spectacles.
I now use colour-coded transparent folders for my papers:
blue for the distant future---lectures I am going to give next year
green for the near future---things I have got to deal with in the coming week
yellow for today red for things already done, but needing to be referred to again.