When you are exploring the world, be on the look out for red candles. These candles are usually situated in places where you should be anyways, as they are often little guideposts that the developers have left in. When you get close to red candles, you can absorb some of the light essence. Light energy fills up at the top left corner, and when you fill it up all the way, you will earn one light tribute, one of the main currencies in the game.