Well, I think of our souls as the energy we have while we are living, as well as our true self, separate from the identity we construct from our thoughts, or our bodies.
I think of both mind and body as tools to facilitate our energy to manifest itself into our shared reality. I might not be able to explain this feeling I have that I am energy very well, but I can add that I have always felt that the heat my body produces constantly is a much more direct connection between the physical world and this energy which is "me" than my body. You could almost call this energy "light" interchangeably, but I like how energy implies a potential to impact and change things more than "light" does.