Kabbalah tells us there are essentially two kinds of personal light: the light we have already assimilated within ourselves -- our inner light, and the light we are yet to take in -- the surrounding light, which we have not yet grown into.
Each of use burns with an inner light, but unless we have reached enlightenment there is still a part of our light which we have not integrated into our consciousness. Our task here on earth is to complete that process of taking in an becoming that light so that we are a complete manifestation of it. This is what evolution is all about.
How do we do this? By finding our limits and pushing against them. For instance, if you have a hard time being generous, then generosity is more a part of your surrounding light, and is something you are working toward becoming. If you are a naturally generous person, then generosity is part of your inner light. By knowing our inadequacies and current limits we become aware of that surrounding light which we are working on becoming.