evidence: But, what I also learned was that, even if I could never come into agreement with someone, if I examined their viewpoint in depth, I would find the very activity of it stimulated creative thought. It’s like clearing clutter from your garage, closet or desk - it opens up space for new things to come into your life. I interpret that "light" Asimov is speaking of as all the new connections you’ll be able to make, the new ideas you’ll be able to form, when you expose yourself to information you’re not familiar with.